Physics GK Questions | Physics Questions Practice Set
Test your knowledge with these 100 Physics GK questions with answers and explanations. This collection covers important topics such as motion, force, work, energy, heat, light, sound, electricity, magnetism, measurements and modern physics. These physics questions are useful for students, general knowledge practice, competitive exams and quick revision.
Q1. What is the SI unit of force?
A. Joule
B. Newton
C. Watt
D. Pascal
View Answer
The SI unit of force is the newton (N).
Q2. What is the SI unit of work?
A. Newton
B. Watt
C. Joule
D. Pascal
View Answer
The SI unit of work is the joule (J).
Q3. Which instrument is used to measure atmospheric pressure?
A. Thermometer
B. Barometer
C. Hygrometer
D. Ammeter
View Answer
A barometer is used to measure atmospheric pressure.
Q4. What is the approximate speed of light in vacuum?
A. 3 × 10⁶ m/s
B. 3 × 10⁷ m/s
C. 3 × 10⁸ m/s
D. 3 × 10⁹ m/s
View Answer
Light travels through vacuum at approximately 3 × 10⁸ metres per second.
Q5. Which quantity is measured in watts?
A. Energy
B. Power
C. Force
D. Pressure
View Answer
The watt (W) is the SI unit of power, which is the rate of doing work.
Q6. Which law states that every action has an equal and opposite reaction?
A. Newton’s First Law
B. Newton’s Second Law
C. Newton’s Third Law
D. Law of Gravitation
View Answer
Newton’s Third Law states that for every action, there is an equal and opposite reaction.
Q7. What is the SI unit of electric current?
A. Volt
B. Ohm
C. Ampere
D. Coulomb
View Answer
The ampere (A) is the SI unit of electric current.
Q8. Which instrument is used to measure electric current?
A. Voltmeter
B. Ammeter
C. Galvanometer only
D. Barometer
View Answer
An ammeter is used to measure electric current in a circuit.
Q9. What is the SI unit of electrical resistance?
A. Volt
B. Ampere
C. Ohm
D. Watt
View Answer
The SI unit of electrical resistance is the ohm (Ω).
Q10. Which law relates voltage, current and resistance?
A. Newton’s Law
B. Ohm’s Law
C. Hooke’s Law
D. Boyle’s Law
View Answer
Ohm’s Law states that, under suitable conditions, voltage is proportional to current: V = IR.
Q11. What is the SI unit of temperature?
A. Celsius
B. Fahrenheit
C. Kelvin
D. Joule
View Answer
Kelvin (K) is the SI base unit of thermodynamic temperature.
Q12. Which device converts electrical energy into mechanical energy?
A. Generator
B. Electric motor
C. Transformer
D. Battery
View Answer
An electric motor converts electrical energy into mechanical energy.
Q13. Which device converts mechanical energy into electrical energy?
A. Motor
B. Generator
C. Transformer
D. Capacitor
View Answer
A generator converts mechanical energy into electrical energy through electromagnetic induction.
Q14. What is the SI unit of frequency?
A. Decibel
B. Hertz
C. Joule
D. Watt
View Answer
The hertz (Hz) is the SI unit of frequency and represents one cycle per second.
Q15. Sound cannot travel through which medium?
A. Solid
B. Liquid
C. Gas
D. Vacuum
View Answer
Sound is a mechanical wave and requires a material medium for propagation.
Q16. Which type of wave is sound in air?
A. Transverse wave
B. Longitudinal wave
C. Electromagnetic wave
D. Radio wave
View Answer
Sound travels through air as a longitudinal mechanical wave, with particles vibrating parallel to the direction of propagation.
Q17. What is the SI unit of pressure?
A. Newton
B. Pascal
C. Joule
D. Watt
View Answer
The pascal (Pa) is the SI unit of pressure.
Q18. Which force keeps planets in orbit around the Sun?
A. Magnetic force
B. Frictional force
C. Gravitational force
D. Nuclear force
View Answer
The gravitational attraction between the Sun and planets keeps the planets in their orbits.
Q19. Who formulated the law of universal gravitation?
A. Albert Einstein
B. Isaac Newton
C. Galileo Galilei
D. James Clerk Maxwell
View Answer
Isaac Newton formulated the law of universal gravitation.
Q20. What is the approximate acceleration due to gravity on Earth?
A. 5.8 m/s²
B. 7.8 m/s²
C. 9.8 m/s²
D. 12.8 m/s²
View Answer
The average acceleration due to gravity near Earth’s surface is approximately 9.8 m/s².
Q21. Which quantity has both magnitude and direction?
A. Scalar
B. Vector
C. Mass
D. Temperature
View Answer
A vector quantity has both magnitude and direction.
Q22. Which of the following is a scalar quantity?
A. Velocity
B. Force
C. Displacement
D. Speed
View Answer
Speed has magnitude but no direction, so it is a scalar quantity.
Q23. What is the SI unit of velocity?
A. km/h
B. m/s
C. m/s²
D. N
View Answer
The SI unit of velocity is metre per second (m/s).
Q24. What is acceleration?
A. Rate of change of distance
B. Rate of change of velocity
C. Rate of change of mass
D. Rate of change of force
View Answer
Acceleration is the rate at which velocity changes with time.
Q25. Which property of matter resists a change in its state of motion?
A. Density
B. Inertia
C. Elasticity
D. Viscosity
View Answer
Inertia is the tendency of an object to resist changes in its state of rest or motion.
Q26. Which law is also known as the law of inertia?
A. Newton’s First Law
B. Newton’s Second Law
C. Newton’s Third Law
D. Law of Conservation of Energy
View Answer
Newton’s First Law describes the tendency of objects to maintain their state of motion unless acted upon by an external unbalanced force.
Q27. What is the formula for kinetic energy?
A. mgh
B. ½mv²
C. Fd
D. VIt
View Answer
The kinetic energy of an object of mass m moving with speed v is ½mv².
Q28. Which energy is possessed by an object because of its position?
A. Kinetic energy
B. Potential energy
C. Electrical energy
D. Sound energy
View Answer
Potential energy is energy stored because of an object’s position or configuration.
Q29. Which law states that energy can neither be created nor destroyed?
A. Law of conservation of energy
B. Newton’s First Law
C. Ohm’s Law
D. Boyle’s Law
View Answer
The law of conservation of energy states that energy can change from one form to another but cannot be created or destroyed.
Q30. What is the SI unit of power?
A. Joule
B. Newton
C. Watt
D. Ampere
View Answer
Power is the rate of doing work and its SI unit is the watt.
Q31. One horsepower is approximately equal to:
A. 246 W
B. 546 W
C. 746 W
D. 946 W
View Answer
One mechanical horsepower is approximately equal to 746 watts.
Q32. Which simple machine is commonly used to draw water from a well?
A. Pulley
B. Screw
C. Wedge
D. Inclined plane
View Answer
A pulley can change the direction of force and make lifting loads easier.
Q33. What is friction?
A. Force that always increases motion
B. Force that opposes relative motion between surfaces
C. Force that produces electricity
D. Force caused only by gravity
View Answer
Friction acts between surfaces in contact and generally opposes their relative motion or tendency to move.
Q34. Which type of friction acts when an object rolls over a surface?
A. Sliding friction
B. Rolling friction
C. Static friction only
D. Fluid friction
View Answer
Rolling friction occurs when an object rolls over a surface.
Q35. Why are the tyres of vehicles provided with grooves?
A. To increase weight
B. To reduce friction completely
C. To improve grip and reduce slipping
D. To increase speed automatically
View Answer
Grooves help tyres maintain better contact with the road, especially by helping remove water.
Q36. What is density?
A. Mass per unit volume
B. Volume per unit mass
C. Force per unit area
D. Mass per unit area
View Answer
Density is defined as mass divided by volume.
Q37. Which principle explains why objects float in water?
A. Archimedes’ principle
B. Ohm’s law
C. Newton’s third law
D. Hooke’s law
View Answer
Archimedes’ principle states that an immersed object experiences an upward buoyant force equal to the weight of the fluid displaced.
Q38. Which instrument is used to measure relative density of liquids?
A. Hydrometer
B. Barometer
C. Ammeter
D. Calorimeter
View Answer
A hydrometer is commonly used to measure the relative density or specific gravity of liquids.
Q39. Why does a ship made of steel float on water?
A. Steel is lighter than water
B. Its hollow shape allows it to displace sufficient water
C. Steel has no weight
D. Gravity does not act on ships
View Answer
A ship’s overall average density is low enough because of its hollow structure, allowing the buoyant force to support its weight.
Q40. At what temperature does pure water freeze at standard atmospheric pressure?
A. 0°C
B. 10°C
C. 32°C
D. 100°C
View Answer
Pure water freezes at 0°C under standard atmospheric pressure.
Q41. At what temperature does water boil at standard atmospheric pressure?
A. 50°C
B. 75°C
C. 100°C
D. 120°C
View Answer
At standard atmospheric pressure, water boils at 100°C.
Q42. Which instrument is used to measure temperature?
A. Barometer
B. Thermometer
C. Ammeter
D. Hygrometer
View Answer
A thermometer is used to measure temperature.
Q43. Heat is transferred through direct contact mainly by:
A. Radiation
B. Conduction
C. Reflection
D. Refraction
View Answer
Conduction is the transfer of heat through direct contact between particles of a substance.
Q44. Heat transfer through the movement of fluids is called:
A. Conduction
B. Convection
C. Radiation
D. Reflection
View Answer
Convection transfers heat through the bulk movement of liquids or gases.
Q45. Heat from the Sun reaches Earth mainly by:
A. Conduction
B. Convection
C. Radiation
D. Diffusion
View Answer
Radiation can travel through the vacuum of space, allowing energy from the Sun to reach Earth.
Q46. Which surface is the best absorber of radiant heat?
A. Shiny white surface
B. Polished silver surface
C. Dull black surface
D. Transparent glass
View Answer
Dull black surfaces are generally good absorbers and emitters of thermal radiation.
Q47. Why are cooking utensils often made of metals?
A. Metals are poor conductors
B. Metals are generally good conductors of heat
C. Metals cannot absorb heat
D. Metals have no thermal expansion
View Answer
Metals generally conduct heat efficiently, making them useful for cookware.
Q48. Which phenomenon causes a rainbow?
A. Dispersion of sunlight
B. Magnetism
C. Total absorption
D. Conduction
View Answer
A rainbow forms through refraction, internal reflection and dispersion of sunlight by water droplets.
Q49. Which colour of visible light has the longest wavelength?
A. Violet
B. Blue
C. Green
D. Red
View Answer
Red light has the longest wavelength among the commonly recognized colours of visible light.
Q50. Which colour of visible light has the shortest wavelength?
A. Red
B. Yellow
C. Green
D. Violet
View Answer
Violet light has the shortest wavelength in the visible spectrum.
Q51. Which phenomenon explains the bending of light when it passes from one medium to another?
A. Reflection
B. Refraction
C. Diffraction
D. Dispersion only
View Answer
Refraction is the change in direction of light when it passes between media with different optical properties.
Q52. Which mirror is commonly used as a rear-view mirror in vehicles?
A. Plane mirror
B. Concave mirror
C. Convex mirror
D. Cylindrical mirror
View Answer
A convex mirror provides a wider field of view and produces an upright, diminished image.
Q53. Which mirror is commonly used by dentists to obtain a magnified image?
A. Convex mirror
B. Concave mirror
C. Plane mirror
D. Rear-view mirror
View Answer
A concave mirror can produce a magnified upright image when the object is placed within its focal length.
Q54. Which lens is used to correct myopia?
A. Convex lens
B. Concave lens
C. Cylindrical lens only
D. Plane glass
View Answer
Myopia, or short-sightedness, is commonly corrected using a concave lens.
Q55. Which lens is used to correct hypermetropia?
A. Concave lens
B. Convex lens
C. Plane lens
D. None
View Answer
Hypermetropia, or long-sightedness, is commonly corrected using a convex lens.
Q56. What is the splitting of white light into its constituent colours called?
A. Reflection
B. Refraction
C. Dispersion
D. Interference
View Answer
Dispersion is the separation of white light into its component colours.
Q57. Which phenomenon explains why the sky appears blue?
A. Reflection
B. Scattering of light
C. Total internal reflection
D. Dispersion by clouds
View Answer
Shorter wavelengths of sunlight are scattered more strongly by molecules in Earth’s atmosphere, contributing to the blue appearance of the sky.
Q58. Why does the Sun appear reddish during sunrise and sunset?
A. Red light is scattered the least over the longer atmospheric path
B. Red light has the highest frequency
C. The Sun becomes colder
D. The atmosphere produces red light
View Answer
At sunrise and sunset, sunlight travels through a longer atmospheric path, causing shorter wavelengths to scatter more strongly and leaving more red and orange light reaching the observer.
Q59. Which phenomenon is responsible for the formation of an echo?
A. Refraction
B. Reflection of sound
C. Absorption of sound
D. Dispersion
View Answer
An echo is produced when reflected sound reaches the listener after a sufficient time interval.
Q60. What is the unit commonly used to express sound intensity level?
A. Hertz
B. Decibel
C. Watt
D. Newton
View Answer
Sound intensity level is commonly expressed in decibels (dB).
Q61. Which characteristic of sound determines its pitch?
A. Amplitude
B. Frequency
C. Speed
D. Intensity only
View Answer
The pitch of a sound is primarily determined by its frequency.
Q62. Which characteristic of sound is mainly related to its loudness?
A. Amplitude
B. Frequency
C. Wavelength only
D. Time period only
View Answer
Greater amplitude generally corresponds to greater perceived loudness.
Q63. Which electromagnetic waves are used in television remote controls?
A. Ultraviolet rays
B. Infrared rays
C. X-rays
D. Gamma rays
View Answer
Most conventional television remote controls use infrared radiation to transmit signals.
Q64. Which electromagnetic waves are used in microwave ovens?
A. Radio waves
B. Microwaves
C. Ultraviolet rays
D. Gamma rays
View Answer
Microwave ovens use electromagnetic waves in the microwave range to heat food.
Q65. Which electromagnetic radiation has the highest frequency?
A. Radio waves
B. Infrared rays
C. X-rays
D. Gamma rays
View Answer
Gamma rays have the highest frequencies and shortest wavelengths in the electromagnetic spectrum.
Q66. Which electromagnetic radiation has the longest wavelength?
A. Gamma rays
B. X-rays
C. Radio waves
D. Ultraviolet rays
View Answer
Radio waves have the longest wavelengths in the electromagnetic spectrum.
Q67. Which radiation is commonly used for sterilization because of its strong ability to damage microorganisms?
A. Infrared
B. Ultraviolet
C. Radio waves
D. Microwaves
View Answer
Ultraviolet-C radiation is used in certain sterilization and disinfection applications because it can damage microbial genetic material.
Q68. Which device is used to convert AC voltage from one level to another?
A. Transformer
B. Motor
C. Ammeter
D. Galvanometer
View Answer
A transformer changes alternating voltage levels through electromagnetic induction.
Q69. A transformer works on the principle of:
A. Electromagnetic induction
B. Electrolysis
C. Thermal expansion
D. Photoelectric effect
View Answer
Transformers operate using electromagnetic induction between their coils.
Q70. Which device protects an electrical circuit from excessive current?
A. Fuse
B. Capacitor
C. Transformer
D. Voltmeter
View Answer
A fuse melts when excessive current flows through it, breaking the circuit and helping protect electrical equipment.
Q71. What is the SI unit of electric charge?
A. Ampere
B. Coulomb
C. Volt
D. Ohm
View Answer
The coulomb (C) is the SI unit of electric charge.
Q72. What is the SI unit of potential difference?
A. Ampere
B. Volt
C. Ohm
D. Coulomb
View Answer
The volt (V) is the SI unit of electric potential difference.
Q73. Which instrument measures potential difference?
A. Ammeter
B. Voltmeter
C. Barometer
D. Thermometer
View Answer
A voltmeter is used to measure potential difference between two points in a circuit.
Q74. How is an ammeter connected in a circuit?
A. In parallel
B. In series
C. Across the battery only
D. Outside the circuit
View Answer
An ammeter is connected in series so that the circuit current passes through it.
Q75. How is a voltmeter connected in a circuit?
A. In series
B. In parallel
C. In the battery only
D. In place of a switch
View Answer
A voltmeter is connected in parallel across the component whose potential difference is being measured.
Q76. Which material is generally a good conductor of electricity?
A. Rubber
B. Glass
C. Copper
D. Plastic
View Answer
Copper has high electrical conductivity and is widely used in electrical wiring.
Q77. Which material is generally an electrical insulator?
A. Copper
B. Aluminium
C. Silver
D. Rubber
View Answer
Rubber has high electrical resistance and is commonly used as an insulating material.
Q78. Which metal has very high electrical conductivity?
A. Iron
B. Silver
C. Lead
D. Mercury
View Answer
Silver has the highest electrical conductivity among metals under ordinary conditions.
Q79. Which effect of electric current is used in an electric heater?
A. Magnetic effect
B. Heating effect
C. Chemical effect only
D. Photoelectric effect
View Answer
Electric heaters work by converting electrical energy into heat through electrical resistance.
Q80. Which effect of electric current is used in an electromagnet?
A. Heating effect
B. Magnetic effect
C. Chemical effect
D. Optical effect
View Answer
An electric current produces a magnetic field, which is used to create electromagnets.
Q81. What happens to the resistance of most metallic conductors when temperature increases?
A. It decreases
B. It generally increases
C. It becomes zero
D. It remains exactly constant
View Answer
For most metals, electrical resistance increases as temperature rises.
Q82. Which particles carry electric current in a metal?
A. Protons
B. Neutrons
C. Free electrons
D. Atoms only
View Answer
In metals, electric current is primarily due to the movement of free electrons.
Q83. Which material is commonly used in the filament of an incandescent bulb?
A. Copper
B. Tungsten
C. Aluminium
D. Silver
View Answer
Tungsten has a very high melting point and is suitable for incandescent bulb filaments.
Q84. Which phenomenon is the basis of a solar cell?
A. Photoelectric effect
B. Photovoltaic effect
C. Magnetic effect
D. Heating effect
View Answer
Solar cells convert light energy directly into electrical energy through the photovoltaic effect.
Q85. Who explained the photoelectric effect using quantum theory?
A. Isaac Newton
B. Albert Einstein
C. Michael Faraday
D. James Watt
View Answer
Albert Einstein explained the photoelectric effect using the concept of light quanta and received the Nobel Prize in Physics partly for this work.
Q86. Which particle has a negative electric charge?
A. Proton
B. Neutron
C. Electron
D. Positron
View Answer
An electron carries a negative elementary electric charge.
Q87. Which particle has a positive electric charge?
A. Electron
B. Proton
C. Neutron
D. Photon
View Answer
A proton carries a positive elementary electric charge.
Q88. Which subatomic particle has no electric charge?
A. Electron
B. Proton
C. Neutron
D. Positron
View Answer
A neutron has no net electric charge.
Q89. Which particle is found in the nucleus of an atom?
A. Electron only
B. Proton and neutron
C. Photon only
D. Electron and photon
View Answer
The nucleus of an ordinary atom contains protons and neutrons, while electrons occupy regions around the nucleus.
Q90. Which force holds protons and neutrons together in the atomic nucleus?
A. Gravitational force
B. Strong nuclear force
C. Frictional force
D. Magnetic force only
View Answer
The strong nuclear interaction is responsible for binding quarks and, at the nuclear scale, contributes to the binding of nucleons within atomic nuclei.
Q91. Which scientist proposed the nuclear model of the atom based on the gold foil experiment?
A. J. J. Thomson
B. Ernest Rutherford
C. Niels Bohr
D. James Chadwick
View Answer
Rutherford’s gold foil experiment led to the nuclear model of the atom.
Q92. Who discovered the electron?
A. J. J. Thomson
B. Rutherford
C. Bohr
D. Chadwick
View Answer
J. J. Thomson is credited with the discovery of the electron through experiments with cathode rays.
Q93. Who discovered the neutron?
A. J. J. Thomson
B. Ernest Rutherford
C. James Chadwick
D. Niels Bohr
View Answer
James Chadwick discovered the neutron in 1932.
Q94. Which phenomenon involves the spontaneous emission of radiation from unstable atomic nuclei?
A. Reflection
B. Radioactivity
C. Refraction
D. Conduction
View Answer
Radioactivity is the spontaneous transformation of unstable atomic nuclei accompanied by the emission of radiation.
Q95. Which radiation has the greatest penetrating power among alpha, beta and gamma radiation?
A. Alpha rays
B. Beta rays
C. Gamma rays
D. All have equal penetration
View Answer
Gamma radiation has much greater penetrating ability than alpha or beta radiation.
Q96. Which radiation is positively charged?
A. Alpha radiation
B. Beta-minus radiation
C. Gamma radiation
D. X-rays
View Answer
An alpha particle consists of two protons and two neutrons and therefore carries a positive charge.
Q97. Which radiation has no electric charge?
A. Alpha rays
B. Beta rays
C. Gamma rays
D. Proton rays
View Answer
Gamma rays are high-energy electromagnetic radiation and have no electric charge.
Q98. Which SI unit is used to measure radioactivity?
A. Gray
B. Sievert
C. Becquerel
D. Tesla
View Answer
The becquerel (Bq) is the SI unit of activity, equal to one nuclear decay per second.
Q99. Which SI unit is used for magnetic flux density?
A. Weber
B. Tesla
C. Henry
D. Gauss only
View Answer
The tesla (T) is the SI unit of magnetic flux density.
Q100. Which scientist is associated with the theory of relativity?
A. Isaac Newton
B. Albert Einstein
C. Michael Faraday
D. Galileo Galilei
View Answer
Albert Einstein developed the special and general theories of relativity, which fundamentally changed our understanding of space, time, gravity and motion.
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