Physics | General Science One Liners 2026 | Best Physics, Chemistry, Biology Questions

Everyday Science one liner - Physics

1. Units and Measurements

What are the base units in the International System of Units (SI) called? - Fundamental Units
How many fundamental units are defined in the modern SI system? - 7
How many supplementary units exist in the SI system (plane angle and solid angle)? - 2
What is the SI unit of luminous intensity? - Candela (cd)
What is the SI unit of amount of substance? - Mole (mol)
What is the SI base unit of thermodynamic temperature? - Kelvin (K)
Which practical unit of astronomical distance represents the distance traveled by light in a vacuum in one year? - Light-year
Approximately how many meters are in one light-year? - $9.46 \times 10^{15}$ meters
What is the largest practical astronomical unit of distance, equal to about 3.26 light-years? - Parsec
What is the mean distance between the center of the Earth and the Sun called? - Astronomical Unit (AU)
Which unit of length equals $10^{-10}$ meters and is used to measure wavelengths of light? - Angstrom (Å)
Which unit equals $10^{-15}$ meters and is used to express nuclear dimensions? - Fermi (Femtometer)
What unit of distance used in maritime and air navigation equals 1,852 meters? - Nautical Mile
In which unit is the navigational speed of ships and sea vessels measured? - Knot
What is the SI unit of force? - Newton (N)
What is the CGS unit of force? - Dyne
How many dynes make up one Newton? - $10^5$ dynes
What is the SI unit of work and energy? - Joule (J)
What is the CGS unit of work and energy? - Erg
How many ergs are equal to one Joule? - $10^7$ ergs
What is the SI unit of power? - Watt (W)
One horsepower (hp) is equal to how many Watts? - 746 Watts
What is the SI unit of frequency? - Hertz (Hz)
What is the SI unit of electric charge? - Coulomb (C)
What is the SI unit of electric potential difference (voltage)? - Volt (V)
What is the SI unit of electrical resistance? - Ohm ($\Omega$)
What is the SI unit of electrical conductance? - Siemens (S)
What is the SI unit of magnetic flux? - Weber (Wb)
What is the SI unit of magnetic flux density (magnetic field)? - Tesla (T)
What is the CGS unit of magnetic field strength? - Gauss (G)
What is the SI unit of electrical inductance? - Henry (H)
What is the SI unit of electrical capacitance? - Farad (F)
What is the SI unit of pressure? - Pascal (Pa)
One bar of atmospheric pressure is equal to how many Pascals? - $10^5$ Pascals
One Torr of pressure is equal to the pressure exerted by how many millimeters of mercury column? - 1 mm of Hg
What is the SI unit of radioactivity? - Becquerel (Bq)
In which unit is the optical power of a corrective lens measured? - Diopter (D)
Which logarithmic unit is used to measure sound intensity levels? - Decibel (dB)
One micron ($\mu$m) is equal to how many meters? - $10^{-6}$ meters
One nanometer (nm) is equal to how many meters? - $10^{-9}$ meters
Which unit equal to $10^{-28}\text{ m}^2$ is used in nuclear physics to measure the cross-sectional area of nuclei? - Barn
Which instrument is used to measure atmospheric pressure? - Barometer
Which instrument is used in aircraft to measure altitude above sea level? - Altimeter
Which instrument is connected in series to measure electric current in a circuit? - Ammeter
Which instrument is connected in parallel to measure electric potential difference? - Voltmeter
Which instrument is used to detect and indicate the direction of small electric currents? - Galvanometer
Which instrument is used to measure the relative density and purity of milk? - Lactometer
Which instrument is used to measure the humidity or moisture content of air? - Hygrometer
Which instrument is used to measure wind speed? - Anemometer
Which instrument is used to measure very high temperatures without physical contact? - Pyrometer

2. Motion, Force, and Laws of Motion

Which quantity represents the shortest straight-line distance between initial and final points? - Displacement
What is the time rate of change of displacement called? - Velocity
What is the time rate of change of velocity called? - Acceleration
Which law states that an object remains at rest or in uniform motion unless acted upon by an external unbalanced force? - Newton's First Law of Motion
Which physical property describes an object's resistance to any change in its state of rest or motion? - Inertia
What fundamental quantity determines the amount of inertia an object possesses? - Mass
Why do passengers fall backward when a stationary bus suddenly starts moving? - Inertia of Rest
Why do passengers lean forward when a moving bus suddenly stops? - Inertia of Motion
Why does dust separate from a carpet when it is beaten with a stick? - Inertia of Rest
Why does mud fly off tangentially from rotating vehicle tires? - Inertia of Direction
What is the product of an object's mass and its velocity called? - Linear Momentum
Which law states that the rate of change of momentum is directly proportional to the applied force ($F = ma$)? - Newton's Second Law of Motion
What is the product of a large force and the short time interval over which it acts called? - Impulse
Why does a cricket fielder pull his hands backward while catching a fast-moving ball? - To increase impact time and reduce impulsive force
Why are shock absorbers fitted in motor vehicles? - To increase impact time and reduce force during bumps
Which law states that for every action, there is an equal and opposite reaction? - Newton's Third Law of Motion
What causes a gun to recoil backward when a bullet is fired forward? - Newton's Third Law of Motion (Reaction Force)
On which law of motion and conservation principle does rocket propulsion primarily operate? - Law of Conservation of Linear Momentum
What contact force always opposes relative motion between two surfaces in contact? - Friction
What is the maximum value of static friction just before an object starts sliding called? - Limiting Friction
Which type of friction is significantly lower than sliding friction and utilized in ball bearings? - Rolling Friction
Why do automobile tires have grooved treads on their surfaces? - To increase friction and prevent skidding
What substances are applied to machine parts to reduce frictional wear and heat? - Lubricants
What is the center-seeking force required to keep an object moving in a circular path called? - Centripetal Force
Why are curved railway tracks and roads banked with an elevated outer edge? - To provide necessary centripetal force
What outward pseudo-force is experienced by an object in a rotating frame of reference? - Centrifugal Force
On which physical force principle does a milk cream separator and spin dryer operate? - Centrifugal Force
What geometric shape does the path of an airborne projectile follow under gravity alone? - Parabola
At what launch angle does a projectile achieve its maximum horizontal range (ignoring air resistance)? - 45 degrees
What is the vertical component of velocity at the highest point of a projectile's flight? - Zero
Why do heavy and light objects dropped simultaneously in a vacuum hit the ground together? - Acceleration due to gravity is independent of mass
Why is it difficult to walk on smooth, frictionless ice? - Lack of sufficient frictional force to push backward
Why are airplanes and bullet trains given streamlined shapes? - To reduce fluid friction (air drag)
What is the maximum constant falling velocity attained when air resistance balances gravity? - Terminal Velocity
Why do falling raindrops reach a steady terminal speed instead of continuously accelerating? - Viscous drag of the atmosphere
What is the mathematical formula for the momentum ($p$) of an object? - $p = mv$
What remains constant in an isolated system with no external forces acting on it? - Total Linear Momentum
What is the force exerted on an object moving in a circle of radius $r$ at velocity $v$? - Centripetal Force ($F = \frac{mv^2}{r}$)
In uniform circular motion, which property changes continuously while speed remains constant? - Direction of Velocity
What type of motion involves constant speed along a circular track with non-zero acceleration? - Uniform Circular Motion
What happens to a passenger sitting inside a car when it takes a sharp left turn? - Leans outward to the right due to inertia
What is the SI unit of momentum? - kg·m/s
What is the SI unit of impulse? - N·s (or kg·m/s)
What happens to an object when the net unbalanced force acting on it is zero? - It maintains constant velocity (or rest)
What kind of physical quantity is force (scalar or vector)? - Vector Quantity
What kind of physical quantity is momentum? - Vector Quantity
What happens to the stopping distance of a car if its speed is doubled (under uniform braking)? - It increases fourfold
What term describes a frame of reference in which Newton's first law does not hold without fictitious forces? - Non-Inertial Reference Frame
What is the reaction force when a swimmer pushes water backward? - Water pushes the swimmer forward
Why does a stepping passenger push a small rowboat backward away from the riverbank? - Equal and opposite reaction force

3. Work, Energy, and Power

In physics, what is work done when the applied force and displacement are perpendicular ($\theta = 90^\circ$)? - Zero
Why is the work done against gravity by a porter carrying a load on his head on a flat road zero? - Force and displacement are perpendicular ($\cos 90^\circ = 0$)
What is the work done by centripetal force on an object in a circular orbit? - Zero
What type of work is done by the force of friction against a sliding box? - Negative Work
What is the energy possessed by an object due to its motion called? - Kinetic Energy
What is the mathematical formula for Kinetic Energy? - $\text{KE} = \frac{1}{2}mv^2$
By what factor does the kinetic energy of an object increase if its speed is doubled? - 4 times
By what factor does kinetic energy change if the momentum of a body is doubled? - Increases 4 times ($\text{KE} = \frac{p^2}{2m}$)
What is the energy possessed by an object due to its position, elevation, or configuration called? - Potential Energy
What is the gravitational potential energy of an object of mass $m$ at height $h$? - $mgh$
What type of energy is stored in a stretched bow or a compressed mechanical spring? - Elastic Potential Energy
What form of energy is possessed by water stored behind a high hydroelectric dam? - Gravitational Potential Energy
Which theorem states that net work done on an object equals the change in its kinetic energy? - Work-Energy Theorem
Which fundamental law states that energy can neither be created nor destroyed, only transformed? - Law of Conservation of Energy
What happens to the sum of potential and kinetic energy of an object falling freely under gravity in a vacuum? - Remains Constant
What is the potential energy of a simple pendulum at its maximum displacement (extreme position)? - Maximum
What is the kinetic energy of a simple pendulum at its lowest (mean) position? - Maximum
Which device converts sound energy directly into electrical energy? - Microphone
Which device converts electrical energy into sound energy? - Loudspeaker
Which device converts electrical energy into mechanical energy? - Electric Motor
Which device converts mechanical energy into electrical energy using electromagnetic induction? - Electric Generator (Dynamo)
Which device converts incident light energy directly into electrical energy? - Solar Cell (Photovoltaic Cell)
Which device transforms stored chemical energy into electrical energy? - Electric Cell (Battery)
What energy conversion takes place during photosynthesis in green plants? - Light Energy into Chemical Energy
What is the rate of doing work or consuming energy called? - Power
What is the SI unit of power? - Watt (W)
How many Joules are equivalent to one kilowatt-hour (1 kWh)? - $3.6 \times 10^6$ Joules ($3.6\text{ MJ}$)
What is one kilowatt-hour (1 kWh) of electricity commercially called? - 1 Board of Trade (BOT) Unit
Energy sources that replenish naturally on human timescales are called what? - Renewable Energy Sources
Which fossil fuel sources deplete upon extraction and cannot be quickly replenished? - Non-Renewable Energy Sources
Which renewable energy technology converts moving air currents into rotational power? - Wind Turbine
What is the primary combustible gas present in Biogas? - Methane ($\text{CH}_4$)
Which type of energy harnesses natural thermal heat from within the Earth's crust? - Geothermal Energy
Which power system exploits the temperature difference between warm ocean surface water and cold deep water? - Ocean Thermal Energy Conversion (OTEC)
What form of energy utilizes the gravitational pull of the Moon and Sun on sea levels? - Tidal Energy
What process powers nuclear energy in commercial atomic power plants? - Nuclear Fission
What process generates the light and heat energy produced inside the core of the Sun? - Nuclear Fusion
Which famous equation by Albert Einstein demonstrates mass-energy equivalence? - $E = mc^2$
What is the ratio of Load to Effort in a simple machine called? - Mechanical Advantage (MA)
What is the ratio of distance moved by effort to distance moved by load in a machine? - Velocity Ratio (VR)
What is the relationship between Mechanical Advantage, Velocity Ratio, and Efficiency ($\eta$)? - $\eta = \frac{\text{MA}}{\text{VR}}$
Why can no real machine have an efficiency equal to or greater than 100%? - Energy losses due to friction and heat
What is the power of a machine that does 1 Joule of work in 1 second? - 1 Watt
What type of energy is stored in fossil fuels like coal and petroleum? - Chemical Energy
In an electric iron or toaster, into what form is electrical energy converted? - Heat Energy
What energy transformation occurs in a steam engine? - Heat Energy into Mechanical Energy
What is the work done when a force moves an object in the exact direction of the force? - Positive Work
What is the scalar product of force and displacement vectors equal to? - Work Done
In which unit is human dietary metabolic energy intake commonly expressed? - Calorie (or Kilocalorie)
One dietary kilocalorie (kcal) equals approximately how many Joules? - 4,184 Joules

4. Gravitation and Pressure

Who formulated the Universal Law of Gravitation? - Sir Isaac Newton
What is the value of the Universal Gravitational Constant ($G$)? - $6.674 \times 10^{-11}\text{ N}\cdot\text{m}^2/\text{kg}^2$
Who first experimentally measured the value of $G$ using a torsion balance in 1798? - Henry Cavendish
What is the standard average acceleration due to gravity ($g$) at sea level on Earth? - $9.8\text{ m/s}^2$
Where on the Earth's surface is the value of acceleration due to gravity ($g$) maximum? - At the Poles
Where on the Earth's surface is the value of acceleration due to gravity ($g$) minimum? - At the Equator
What happens to the value of $g$ as an object is taken higher above the Earth's surface? - It Decreases
What happens to the value of $g$ as one moves deeper below the Earth's surface? - It Decreases
What is the value of acceleration due to gravity at the exact center of the Earth? - Zero ($g = 0$)
What would happen to the value of $g$ at the equator if the Earth stopped rotating? - It would Increase
What is the measure of the quantity of matter contained in a body called? - Mass
What is the downward gravitational force acting on a body called ($W = mg$)? - Weight
What is the ratio of acceleration due to gravity on the Moon compared to that on Earth? - Approximately 1/6th
If a person's mass is 60 kg on Earth, what will be their mass on the surface of the Moon? - 60 kg
What is the apparent weight of an astronaut inside an unpowered orbiting spacecraft? - Zero (Weightlessness)
What happens to the apparent weight of a person in an elevator accelerating upward? - It Increases ($R = m(g+a)$)
What happens to the apparent weight of a person in an elevator accelerating downward? - It Decreases ($R = m(g-a)$)
What is the apparent weight of a person in an elevator whose cables snap (free fall)? - Zero
What is the minimum velocity needed for an object to permanently escape Earth's gravity? - Escape Velocity
What is the escape velocity from the surface of the Earth? - $11.2\text{ km/s}$
Why does the Moon lack a permanent atmosphere? - Low escape velocity ($2.38\text{ km/s}$) compared to thermal gas speeds
At what approximate altitude above Earth's equator do geostationary satellites orbit? - $35,786\text{ km}$
What is the orbital period of a geostationary satellite? - 24 hours (West to East)
What is thrust force acting perpendicularly per unit area called? - Pressure ($P = \frac{F}{A}$)
What is the SI unit of pressure? - Pascal (Pa)
Why do cutting knives and needles have sharp, pointed edges? - To reduce area and maximize cutting pressure
Why are wide continuous tracks used on heavy army battle tanks and bulldozers? - To increase surface area and reduce pressure on the ground
Why are the shoulder straps of school bags made wide? - To reduce pressure on the shoulders
What is standard atmospheric pressure at mean sea level in millimeters of mercury? - 760 mm of Hg
What happens to atmospheric pressure as altitude increases into the mountains? - It Decreases
Why does water boil at a temperature below $100^\circ\text{C}$ on high mountain tops? - Decreased atmospheric pressure lowers the boiling point
Why does a pressure cooker cook food significantly faster? - Higher internal pressure raises the boiling point of water
Why do fountain pens often leak ink in high-altitude airplane cabins? - Internal ink pressure exceeds reduced cabin air pressure
What does a sudden, sharp drop in a barometer's mercury column indicate? - Approaching Storm or Cyclone
What does a gradual, steady decrease in barometric reading indicate? - Likelihood of Rain
What does a gradual, steady rise in barometric reading indicate? - Fair and Clear Weather
What is the formula for hydrostatic fluid pressure at depth $h$ in a liquid of density $\rho$? - $P = h\rho g$
Why are the base walls of water reservoir dams built much thicker than the top? - Liquid pressure increases with depth
Which law states that pressure applied to an enclosed fluid is transmitted equally in all directions? - Pascal’s Law
On which physical law do hydraulic brakes, hydraulic jacks, and hydraulic presses operate? - Pascal’s Law
Which principle states that an immersed body experiences an upward buoyant force equal to the weight of fluid displaced? - Archimedes’ Principle
What is the upward force exerted by a fluid on an immersed body called? - Buoyant Force (Upthrust)
Why does a heavy iron ship float on water while a small solid iron ball sinks? - Ship's hollow hull displaces a volume of water equal to its total weight
Why does an iron nail sink in water but float on liquid mercury? - Density of mercury is greater than the density of iron
What fraction of an iceberg's volume remains submerged below the surface of seawater? - Approximately 9/10th
What happens to the water level in a glass when a floating ice cube melts completely? - Remains Unchanged
Why is it easier for a person to swim in seawater than in fresh river water? - Higher saline water density provides greater buoyant upthrust

5. Optics (Light)

What type of wave is light classified as? - Electromagnetic Transverse Wave
What is the speed of light in a vacuum? - $3 \times 10^8\text{ m/s}$ ($300,000\text{ km/s}$)
Approximately how long does sunlight take to travel to the Earth's surface? - 8 minutes 20 seconds (500 seconds)
How long does light reflected from the Moon take to reach the Earth? - Approximately 1.28 seconds
What type of image is always formed by a flat plane mirror? - Virtual, Erect, and Same Size (Laterally Inverted)
What minimum vertical mirror height is needed for a person to view their complete image? - Half of the person's height
How many images are formed when an object is placed between two parallel plane mirrors? - Infinite
Which optical instrument uses multiple reflections inside a tube to create symmetrical patterns? - Kaleidoscope
Which type of spherical mirror is used as a shaving and dental examination mirror? - Concave Mirror
Which type of mirror is used in automobile headlights and searchlight reflectors? - Concave Mirror
Which type of mirror is used as a driver's rear-view side mirror in motor vehicles? - Convex Mirror
Why are convex mirrors preferred as vehicle rear-view mirrors? - They provide an erect, diminished image with a wide field of view
What optical phenomenon describes the bending of light as it passes from one medium to another? - Refraction of Light
When a ray of light enters an optically denser medium from a rarer medium, how does it bend? - Towards the Normal
When a ray of light enters a rarer medium from a denser medium, how does it bend? - Away from the Normal
Which law relates the angle of incidence to the angle of refraction ($\frac{\sin i}{\sin r} = \mu$)? - Snell’s Law
Why does a straight coin at the bottom of a water container appear slightly raised? - Refraction of Light
Why does a straight pencil partially immersed in water appear bent at the surface? - Refraction of Light
What optical phenomenon causes the twinkling of stars at night? - Atmospheric Refraction of Starlight
Why does the Sun appear visible slightly before sunrise and after sunset? - Atmospheric Refraction
What is the angle of incidence called when the corresponding angle of refraction in the rarer medium is $90^\circ$? - Critical Angle
What optical phenomenon occurs when light in a denser medium strikes a boundary beyond the critical angle? - Total Internal Reflection (TIR)
Which optical principle causes the intense sparkling brilliance of a cut diamond? - Total Internal Reflection
What optical illusion in hot deserts makes distant wet pools appear on hot ground? - Mirage (caused by TIR)
On which optical principle do telecommunication optical fibers transmit light signals? - Total Internal Reflection
Which medical instrument uses optical fiber bundles to view inside human internal organs? - Endoscope
What is the separation of white light into its constituent colors by a glass prism called? - Dispersion of Light
Who first demonstrated that white sunlight is composed of seven constituent colors using a prism? - Sir Isaac Newton
Which visible spectral color undergoes the maximum bending (deviation) in a prism? - Violet
Which visible spectral color undergoes the minimum bending (deviation) in a prism? - Red
Which color in the visible spectrum has the longest wavelength and lowest frequency? - Red
Which color in the visible spectrum has the shortest wavelength and highest frequency? - Violet
What natural phenomenon involves dispersion, refraction, and internal reflection in raindrops? - Rainbow
Which law states that light scattering intensity is inversely proportional to $\lambda^4$? - Rayleigh’s Scattering Law
Why does the clear daytime sky appear blue? - Preferential scattering of shorter blue wavelengths by air molecules
Why does the Sun appear reddish during sunrise and sunset? - Longer red wavelengths scatter least through the thick atmosphere
What color does the sky appear to an astronaut in outer space or on the Moon? - Black (Dark)
Why is red color used universally for danger signals and traffic stoplights? - It has the longest wavelength and scatters least in fog and dust
What vision defect prevents clear focusing on distant objects (nearsightedness)? - Myopia
Where is the image formed in an uncorrected myopic eye for distant objects? - In front of the Retina
Which type of lens is prescribed to correct Myopia? - Concave (Diverging) Lens
What vision defect prevents clear focusing on nearby objects (farsightedness)? - Hypermetropia
Where is the image formed in an uncorrected hypermetropic eye for nearby objects? - Behind the Retina
Which type of lens is prescribed to correct Hypermetropia? - Convex (Converging) Lens
Which age-related defect of vision reduces the eye's power of accommodation? - Presbyopia
What type of lens is used to correct Presbyopia? - Bifocal Lens
Which vision defect caused by irregular corneal curvature is corrected by cylindrical lenses? - Astigmatism
On which light-sensitive screen at the back of the human eye are images formed? - Retina
What type of image is naturally formed on the human retina? - Real and Inverted
What is the least distance of distinct vision (near point) for a normal healthy human eye? - 25 cm

6. Sound and Waves

What type of wave is sound classified as in air and gases? - Longitudinal Mechanical Wave
Why can sound waves not travel through outer space or a vacuum? - Sound requires a material medium to propagate
What alternating regions of high and low density make up a longitudinal sound wave? - Compressions and Rarefactions
In which state of matter does sound travel with the highest velocity? - Solids
In which state of matter does sound travel with the slowest velocity? - Gases
What is the speed of sound in dry air at $0^\circ\text{C}$? - Approximately $331\text{ m/s}$
What is the speed of sound in air at normal room temperature ($20^\circ\text{C}$)? - Approximately $343\text{ m/s}$
By how much does the speed of sound in air increase per $1^\circ\text{C}$ rise in temperature? - $0.61\text{ m/s}$
Why does sound travel faster in moist (humid) air than in dry air? - Moist air has lower density than dry air
What effect does a change in air pressure alone have on the speed of sound at constant temperature? - No Effect
What is the normal audible frequency range for human ears? - 20 Hz to 20,000 Hz (20 kHz)
What are sound waves with frequencies below 20 Hz called? - Infrasonic Waves (Infrasound)
What are sound waves with frequencies above 20,000 Hz called? - Ultrasonic Waves (Ultrasound)
What natural phenomenon produces infrasonic acoustic waves? - Earthquakes and Volcanic Eruptions
Which animals navigate and hunt in dark environments using ultrasonic echolocation? - Bats and Dolphins
Which system uses ultrasound to detect underwater obstacles and measure sea depth? - SONAR (Sound Navigation and Ranging)
What medical diagnostic technique uses high-frequency ultrasonic waves to visualize organs? - Ultrasonography
What medical procedure uses focused ultrasonic sound waves to break down kidney stones? - Lithotripsy
Which high-frequency whistle produces ultrasonic sound used in dog training? - Galton’s Whistle
Which perceptual characteristic of sound is determined primarily by wave frequency? - Pitch (Shrillness)
Why is a woman's or child's voice generally shriller than an adult male's voice? - Higher frequency and higher pitch
Which perceptual characteristic of sound is determined by wave amplitude? - Loudness
Which property of sound allows a listener to distinguish between different musical instruments playing the same note? - Quality (Timbre)
What is the distinct repetition of sound caused by reflection from a distant obstacle called? - Echo
What is the minimum distance between source and reflector required to hear a distinct echo in air? - 17.2 meters
What is the persistence of hearing duration in the human brain? - 0.1 seconds (1/10th of a second)
What is the persistence of sound in an enclosed hall due to repeated reflections called? - Reverberation
Why are walls and ceilings of movie theaters and auditoriums covered with porous sound-absorbing materials? - To prevent excessive reverberation
What phenomenon occurs when an external driving frequency matches a system's natural frequency, causing large vibrations? - Resonance
Why are marching soldiers ordered to break step while crossing a suspension bridge? - To prevent resonance that could collapse the bridge
What is the ratio of an aircraft's speed to the speed of sound in the surrounding medium called? - Mach Number
What term describes speeds that exceed Mach 1? - Supersonic Speed
What term describes speeds that exceed Mach 5? - Hypersonic Speed
What loud explosive sound is generated on the ground when an aircraft travels faster than sound? - Sonic Boom
What is the apparent shift in sound frequency due to relative motion between source and listener called? - Doppler Effect
Why does an approaching train horn sound higher in pitch than when it moves away? - Doppler Effect
Which acoustic medical instrument functions via multiple reflections of heart and lung sounds inside hollow tubes? - Stethoscope
Why do sound waves easily bend (diffract) around open doorways compared to light waves? - Sound wavelengths are comparable in size to door openings
What is the normal intensity level of ordinary human conversation in decibels? - 40 to 60 dB
Above what continuous noise level does sound become hazardous to human hearing? - 85 dB
What decibel level marks the human threshold of physical auditory pain? - 120 dB
What parameter is calculated as the distance between two consecutive wave crests or compressions? - Wavelength ($\lambda$)
What is the mathematical relation connecting wave velocity ($v$), frequency ($f$), and wavelength ($\lambda$)? - $v = f \lambda$
What remains unchanged when a sound wave passes from air into water? - Frequency
What is the unit used to measure the pitch or frequency of sound vibrations? - Hertz (Hz)
What type of wave can propagate through liquid interiors: transverse or longitudinal? - Longitudinal Waves
Why is the lightning flash seen several seconds before thunder is heard during a storm? - Speed of light is vastly greater than speed of sound
What type of sound wave is generated across the surface of water when a stone is dropped? - Transverse and Surface Waves
What is the term for reflected sound used by marine animals and submarines to navigate? - Echolocation

7. Heat and Thermodynamics

What form of thermal energy transfers between systems due to a temperature difference? - Heat
What physical quantity measures the average kinetic energy of constituent particles in matter? - Temperature
What is the amount of heat needed to raise the temperature of 1 gram of water by $1^\circ\text{C}$ called? - Calorie
One calorie is equal to how many Joules? - 4.184 Joules
At what numerical temperature do both the Celsius and Fahrenheit scales read the exact same value? - $-40^\circ$ ($-40^\circ\text{C} = -40^\circ\text{F}$)
What is the theoretical lowest possible temperature where molecular motion ceases? - Absolute Zero (0 Kelvin or $-273.15^\circ\text{C}$)
What is the normal core body temperature of a healthy human in Celsius? - $37^\circ\text{C}$
What is the normal core body temperature of a healthy human in Fahrenheit? - $98.6^\circ\text{F}$
What is the normal core body temperature of a healthy human in Kelvin? - $310.15\text{ K}$
What is the standard temperature range marked on a clinical mercury thermometer? - $35^\circ\text{C}$ to $42^\circ\text{C}$ ($95^\circ\text{F}$ to $108^\circ\text{F}$)
Why are small gaps left between consecutive sections of steel railway tracks? - To allow for thermal expansion during hot summers
Why are metallic electric transmission wires strung loosely between utility poles? - To prevent snapping due to contraction during cold winters
At what temperature does pure liquid water reach its maximum density and minimum volume? - $4^\circ\text{C}$
What unusual behavior describes water expanding as it cools from $4^\circ\text{C}$ down to $0^\circ\text{C}$? - Anomalous Expansion of Water
How do freshwater fish and aquatic organisms survive in frozen lakes during severe winter? - Water beneath surface ice remains liquid at $4^\circ\text{C}$
Why do glass bottles completely filled with water burst when frozen in a freezer? - Water expands upon freezing below $4^\circ\text{C}$
Which mode of heat transfer in solids occurs via atomic vibrations and electron collisions without bulk motion? - Conduction
Which metal is the best conductor of heat and electricity? - Silver
Why are cooking utensils made of metals like copper and aluminum fitted with wooden or Bakelite handles? - Wood and Bakelite are thermal insulators
Which mode of heat transfer in fluids occurs via the actual circulating bulk movement of heated matter? - Convection
By which heat transfer process do domestic room heaters, geysers, and kitchen chimneys operate? - Convection
What coastal wind phenomena are driven by natural convection currents between land and sea? - Sea Breeze and Land Breeze
Which mode of heat transfer occurs through electromagnetic infrared waves without needing any medium? - Radiation
How does solar heat energy travel across the vacuum of space to reach the Earth? - Radiation
What idealized physical body absorbs all incident electromagnetic radiation falling upon it? - Blackbody
Which law of radiation states that good absorbers of heat are also good emitters? - Kirchhoff’s Law of Radiation
Why is wearing white or light-colored clothing preferred during hot sunny summers? - White surfaces reflect radiant heat
Why are dark or black clothes preferred during cold winters? - Dark surfaces absorb radiant heat
Why is the exterior bottom surface of cooking pans often made rough and black? - To absorb radiant heat rapidly
Which law states that total heat radiated per second by a blackbody is proportional to $T^4$? - Stefan-Boltzmann Law
Which law states that the rate of cooling of a body is proportional to the temperature difference with surroundings? - Newton’s Law of Cooling
Which device minimizes heat transfer by conduction, convection, and radiation using a vacuum and silvered walls? - Thermos Flask (Dewar Flask)
What is the heat energy required to raise the temperature of 1 kg of a substance by 1 Kelvin called? - Specific Heat Capacity
Why is water widely used as an engine coolant in automobiles? - High Specific Heat Capacity ($4184\text{ J/kg}\cdot\text{K}$)
Why is warm water used in hot water bags for pain relief compresses? - Water retains heat for a long duration due to high specific heat
What is the heat absorbed or released during a phase change at constant temperature called? - Latent Heat
What is the latent heat of fusion of ice at $0^\circ\text{C}$ in calories per gram? - $80\text{ cal/g}$ ($3.34 \times 10^5\text{ J/kg}$)
What is the latent heat of vaporization of water at $100^\circ\text{C}$ in calories per gram? - $540\text{ cal/g}$ ($2.26 \times 10^6\text{ J/kg}$)
Why do steam burns at $100^\circ\text{C}$ cause more severe tissue injury than boiling water at $100^\circ\text{C}$? - Steam releases an extra 540 cal/g of latent heat upon condensing
What spontaneous surface cooling process occurs in liquids at temperatures below the boiling point? - Evaporation
Why does water stored in a porous earthen pot (matka) remain cool during summer? - Continuous evaporation through pores extracts latent heat
Why does human sweating (perspiration) cool the skin surface on a hot day? - Evaporating sweat draws latent heat of vaporization from the body
What direct phase transition turns a solid into gas without passing through a liquid phase? - Sublimation
Name a common domestic household substance that undergoes sublimation when exposed to air. - Camphor (or Naphthalene)
What is dry ice chemically composed of? - Solid Carbon Dioxide ($\text{CO}_2$)
Which thermodynamic law provides the basis for the definition of temperature (thermal equilibrium concept)? - Zeroth Law of Thermodynamics
Which law represents the conservation of energy applied to thermodynamic systems ($dQ = dU + dW$)? - First Law of Thermodynamics
Which thermodynamic law establishes that heat cannot spontaneously flow from a colder body to a hotter body? - Second Law of Thermodynamics
What thermodynamic property measures the degree of disorder or randomness in a closed system? - Entropy
Which liquid metal is commonly used inside traditional clinical and laboratory thermometers? - Mercury

8. Electricity and Magnetism

Which fundamental law governs the electrostatic force between two stationary point charges? - Coulomb’s Law
What is the time rate of flow of electric charge across a conductor cross-section called? - Electric Current ($I = \frac{Q}{t}$)
What is the SI unit of electric current? - Ampere (A)
What is the direction of conventional electric current relative to electron movement? - Opposite to electron drift
Which law states that current through a metallic conductor is directly proportional to voltage at constant temperature? - Ohm’s Law ($V = IR$)
What is the resistance of an ideal ammeter? - Zero
What is the resistance of an ideal voltmeter? - Infinite
How does the electrical resistance of pure metallic conductors change when temperature increases? - Increases
How does the electrical resistance of semiconductors like Silicon and Germanium change with temperature rise? - Decreases
What phenomenon describes the complete loss of electrical resistance in materials cooled below critical temperature? - Superconductivity
Who discovered the phenomenon of superconductivity in liquid-helium-cooled mercury in 1911? - Heike Kamerlingh Onnes
In which circuit arrangement does the same current flow sequentially through all connected components? - Series Circuit
In which circuit arrangement do all branches experience the same supply voltage? - Parallel Circuit
How are domestic electrical appliances in households wired together? - Parallel Circuit
What happens to the overall equivalent resistance when multiple resistors are connected in parallel? - Decreases (less than the smallest individual resistor)
Which law states that heat generated in a resistor is proportional to $I^2Rt$? - Joule’s Law of Heating
Which alloy of Nickel and Chromium is used to make heating elements in electric irons and room heaters? - Nichrome
Which metal is used for filaments in incandescent light bulbs due to its very high melting point ($3422^\circ\text{C}$)? - Tungsten
Which inert gases are filled inside incandescent bulbs to prevent filament oxidation? - Argon and Nitrogen
What two key properties must an electric safety fuse wire possess? - High Resistivity and Low Melting Point
What alloy is traditionally used in the fabrication of electric fuse wires? - Alloy of Tin (63%) and Lead (37%)
Which automatic electromagnetic/bimetallic switch has replaced sacrificial fuse wires in modern homes? - Miniature Circuit Breaker (MCB)
What is the standardized voltage and frequency of domestic AC electricity supply in India? - 220 Volts, 50 Hz
In a three-pin domestic plug, what color insulation code is used for the Earth wire in India? - Green (or Green-Yellow)
In a three-pin domestic plug, what color insulation code is used for the Live wire? - Red (or Brown)
In a three-pin domestic plug, what color insulation code is used for the Neutral wire? - Black (or Blue)
Why is the earth pin in a three-pin electrical plug made thicker and longer than the other two pins? - For early grounding safety to discharge fault currents
What is the electrical power consumed by an appliance operating at voltage $V$ with current $I$? - Power ($P = VI = I^2R$)
Who first discovered in 1820 that an electric current creates a magnetic field around it? - Hans Christian Oersted
Which rule gives the direction of concentric magnetic field lines around a straight current wire? - Right-Hand Thumb Rule
What is a tightly wound helical cylindrical coil of insulated wire that behaves like a magnet called? - Solenoid
What temporary magnet consists of a soft iron core placed inside a current-carrying solenoid? - Electromagnet
Which rule is used to determine the direction of mechanical force on a current conductor in a magnetic field? - Fleming’s Left-Hand Rule
Which device converts electrical energy into rotational mechanical energy using Fleming's Left-Hand Rule? - Electric Motor
Who discovered the phenomenon of Electromagnetic Induction (EMI) in 1831? - Michael Faraday
Which law states that the polarity of induced EMF opposes the magnetic flux change producing it? - Lenz’s Law
On which fundamental conservation principle is Lenz’s Law based? - Law of Conservation of Energy
Which rule is used to find the direction of induced electric current in a moving generator conductor? - Fleming’s Right-Hand Rule
Which electrical device converts mechanical rotational energy into electrical energy using EMI? - Electric Generator (Dynamo)
Which static device steps up or steps down alternating voltage (AC) through mutual electromagnetic induction? - Transformer
Why does a transformer fail to operate when connected across a Direct Current (DC) power source? - Steady DC produces no changing magnetic flux
What type of transformer increases alternating output voltage while lowering output current? - Step-Up Transformer
Why is long-distance electricity transmission from power stations carried out at ultra-high voltages? - To minimize $I^2R$ power loss in cables
Do isolated magnetic monopoles exist in nature? - No (Magnetic poles always exist in dipoles)
In which direction do magnetic field lines travel outside a bar magnet? - North Pole to South Pole
In which direction does a freely suspended magnetic compass needle always align itself? - Geographic North-South
Which ferromagnetic alloy of Aluminum, Nickel, and Cobalt is used to make strong permanent magnets? - Alnico
What is the critical temperature above which a ferromagnetic material loses magnetism and becomes paramagnetic? - Curie Temperature

General Science One Liners for Competitive Exams 2026

Everyday Science one liner - Physics

1. Units and Measurements

2. Motion, Force, and Laws of Motion

3. Work, Energy, and Power

4. Gravitation and Pressure

5. Optics (Light)

6. Sound and Waves

7. Heat and Thermodynamics

8. Electricity and Magnetism

Mock Tests for Competitive Exam Preparation