100 Most important General Science (Physics) Questions with Answers for UPSC, SSC, Railways, and other competitive exams:

Mechanics

SI unit of force?

– Newton

Acceleration due to gravity on Earth?

– 9.8 m/s²

SI unit of work?

– Joule

Formula for momentum?

– p = mv

Law of Inertia is also known as?

– Newton’s First Law

SI unit of power?

– Watt

Force × Displacement = ?

– Work

Energy possessed by a moving object?

– Kinetic Energy

Unit of pressure?

– Pascal

Formula for gravitational force?

– F = G (m₁m₂/r²)

Heat and Thermodynamics

SI unit of temperature?

– Kelvin

Absolute zero in Celsius?

– -273.15°C

Heat transfer without a medium?

– Radiation

Heat transfer in liquids?

– Convection

Heat transfer in solids?

– Conduction

Device that measures temperature?

– Thermometer

First law of thermodynamics is based on?

– Conservation of Energy

Entropy measures?

– Disorder

Expansion of liquids on heating?

– Thermal Expansion

Process of direct solid to gas change?

– Sublimation

Sound and Waves

Speed of sound in air?

– 343 m/s

SI unit of frequency?

– Hertz (Hz)

Sound cannot travel in?

– Vacuum

Unit of wavelength?

– Meter

Longitudinal waves example?

– Sound waves

Transverse waves example?

– Light waves

Effect of frequency change due to motion?

– Doppler Effect

Pitch of sound depends on?

– Frequency

Device to measure sound intensity?

– Decibel Meter

Unit of sound intensity?

– Decibel (dB)

Light and Optics

Speed of light in vacuum?

– 3 × 10⁸ m/s

Bending of light in a medium?

– Refraction

Mirror used in car headlights?

– Concave Mirror

Mirror used in shaving?

– Concave Mirror

Lens used in a magnifying glass?

– Convex Lens

Formula for refractive index?

– n = c/v

Unit of lens power?

– Diopter

Prism splits light into?

– Spectrum

Image formed by a plane mirror?

– Virtual and Erect

Device to measure optical power?

– Lensmeter

Electricity and Magnetism

SI unit of electric current?

– Ampere

Ohm’s Law formula?

– V = IR

Charge of an electron?

– -1.6 × 10

⁻

¹⁹ C

SI unit of resistance?

– Ohm

Unit of electric charge?

– Coulomb

Material that does not conduct electricity?

– Insulator

Magnetic field lines move from?

– North to South

Earth’s magnetic field is due to?

– Iron Core

Transformer works on?

– Electromagnetic Induction

Unit of capacitance?

– Farad

Electromagnetic Waves

Longest wavelength EM wave?

– Radio waves

Shortest wavelength EM wave?

– Gamma rays

Sun’s most emitted radiation?

– Infrared

Used for satellite communication?

– Microwaves

UV rays cause?

– Skin Cancer

Discovered X-rays?

– Wilhelm Roentgen

SI unit of frequency?

– Hertz

Gamma rays are used in?

– Cancer Treatment

Device to detect radio waves?

– Antenna

Infrared waves are used in?

– Night Vision

Modern Physics

Who discovered the electron?

– J.J. Thomson

Who discovered the proton?

– Rutherford

Who discovered the neutron?

– Chadwick

Who proposed quantum theory?

– Max Planck

SI unit of energy?

– Joule

Photoelectric effect is explained by?

– Albert Einstein

Mass-energy equivalence formula?

– E = mc²

Charge of neutron?

– Neutral

Unit of radioactivity?

– Becquerel

Nuclear fission discovered by?

– Otto Hahn

Atomic and Nuclear Physics

Lightest element?

– Hydrogen

Heaviest natural element?

– Uranium

Half-life measures?

– Radioactive Decay

Number of protons in oxygen?

– 8

Fuel in nuclear reactors?

– Uranium-235

Fusion occurs in?

– Sun

Isotopes have same?

– Atomic Number

Positron is an anti-particle of?

– Electron

Nuclear reactor moderator?

– Graphite

Device to detect radiation?

– Geiger Counter

Space and Astronomy

Earth’s natural satellite?

– Moon

Hottest planet?

– Venus

Largest planet?

– Jupiter

Closest star to Earth?

– Sun

Galaxy containing Earth?

– Milky Way

Distance light travels in a year?

– Light-year

Telescope that orbits Earth?

– Hubble

First person on the Moon?

– Neil Armstrong

First satellite in space?

– Sputnik-1

Biggest asteroid belt location?

– Between Mars and Jupiter

Miscellaneous Physics Concepts

Law stating energy cannot be created or destroyed?

– Conservation of Energy

Unit of luminous intensity?

– Candela

Law of floating bodies?

– Archimedes’ Principle

Law stating pressure in a fluid is transmitted equally?

– Pascal’s Law

Law governing fluid speed and pressure?

– Bernoulli’s Principle

Force that opposes motion?

– Friction

Force that keeps planets in orbit?

– Gravity

Centrifugal force acts?

– Outward

Centripetal force acts?

– Inward

100. SI unit of angular velocity? – Radian per second