Physics Basics MCQs

Correct Answer: Periscope

A periscope lets a submerged submarine observe the surface.

Correct Answer: Liquids and gases

Convection transfers heat through the bulk movement of fluids — liquids and gases — not through solids or a vacuum.

Correct Answer: Zero

A reversible adiabatic process is isentropic: no heat is exchanged, so the entropy change is zero.

Correct Answer: Dispersion

Dispersion is the splitting of white light into its spectrum of colours, as through a prism.

Correct Answer: Milk

A lactometer measures the specific gravity, and hence the purity, of milk.

Correct Answer: 9.46 trillion km

A light-year — the distance light travels in one year — is about 9.46 trillion kilometres.

Correct Answer: Plasma

After solid, liquid and gas, plasma — ionised gas — is conventionally counted as the fourth state of matter.

Correct Answer: Speed of light

Electromagnetic waves travel in a vacuum at the speed of light, about 300,000 km/s.

Correct Answer: Law of Acceleration

Newton's second law (F = ma) is also called the law of acceleration.

Correct Answer: Longitudinal

In a longitudinal wave the particles vibrate parallel to the direction of travel, as in sound waves.

Correct Answer: Viscosity

The poise (CGS unit) measures dynamic viscosity.

Correct Answer: Provide necessary insulation from heat

Sawdust is a poor conductor of heat and insulates ice blocks from warm air.

Correct Answer: Expansion during heat

Gaps let steel rails expand in summer heat without buckling.

Correct Answer: Ampere

The SI unit of electric current is the ampere: one ampere is one coulomb of charge passing a point per second.

Correct Answer: 32°F

The freezing point of water in Fahrenheit is 32°F, the temperature at which water turns to ice at standard atmospheric pressure.

Correct Answer: 100°C

The boiling point of water in Celsius is 100°C at standard atmospheric pressure (sea level).

Correct Answer: Newton

The SI unit of force is the newton: one newton is the force needed to accelerate a mass of one kilogram by one metre per second squared.

Correct Answer: Distance

The light year is a unit of distance: the distance light travels in one year in a vacuum, about 9.46 trillion kilometres.

Correct Answer: 3 × 10⁸ m/s

The speed of light in vacuum is 3 × 10⁸ m/s (exactly 299,792,458 m/s), the fastest speed in the universe.

Correct Answer: 212°F

The boiling point of water in Fahrenheit is 212°F at standard atmospheric pressure, the same point as 100°C.

Correct Answer: Albert Einstein

Albert Einstein is called the father of modern physics for his theories of relativity, which reshaped physics in the twentieth century.

Correct Answer: Ohm

The unit of electric resistance is the ohm: a conductor has a resistance of one ohm when one volt drives one ampere through it.

Correct Answer: Joule

The SI unit of work is the joule: one joule is the work done when a force of one newton moves an object one metre.

Correct Answer: Watt

The SI unit of power is the watt: one watt is one joule of energy transferred per second.

Correct Answer: Candela

The SI unit of luminous intensity is the candela: it measures how much light a source emits in a particular direction.

Correct Answer: Hertz

The SI unit of frequency is the hertz: one hertz is one cycle per second.

Correct Answer: Solids

The speed of sound is maximum in solids: sound travels fastest where particles are packed tightest, so it is faster in solids than in liquids and slowest in gases (and cannot travel in a vacuum).

Correct Answer: Coulomb

The SI unit of charge is the coulomb: one coulomb is the charge carried by a current of one ampere flowing for one second.

Correct Answer: Volt

The SI unit of voltage is the volt: one volt is the potential difference that drives one ampere through a resistance of one ohm.

Correct Answer: Second

The SI unit of time is the second: the SI base unit, now defined by the caesium-133 atom, with minutes and hours as larger derived units.

Correct Answer: Kelvin

The SI unit of temperature is the kelvin: the SI base unit of thermodynamic temperature, with 0 K (absolute zero) at -273.15°C; Celsius degrees are the same size but counted from water's freezing point.

Correct Answer: Kilogram

The SI unit of mass is the kilogram: the SI base unit of mass, defined since 2019 by the Planck constant; the gram is a thousandth of a kilogram, not the base unit.

Correct Answer: Farad

The SI unit of electric capacitance is the farad: one farad is the capacitance that stores one coulomb of charge at one volt.

Correct Answer: Pascal

The SI unit of pressure is the pascal: one pascal is one newton of force per square metre, so atmospheric pressure at sea level is about 101,325 pascals.

Correct Answer: Lumen

The SI unit of luminous flux is the lumen: it measures the total visible light emitted by a source, while the candela measures intensity in a direction and the lux measures illuminance falling on a surface.

Correct Answer: Henry

The SI unit of inductance is the henry: one henry is the inductance in which a current changing at one ampere per second induces one volt (the farad is capacitance, the ohm resistance, the tesla magnetic flux density).

Correct Answer: Weber

The SI unit of magnetic flux is the weber: one weber is the flux that, falling to zero in one second, induces one volt in a single-turn coil (the tesla is flux density, the henry inductance).

Correct Answer: Decibel

The SI unit of sound intensity is the decibel: sound intensity level is measured in decibels on a logarithmic scale, so a 10 dB rise means ten times the intensity (the hertz is frequency, the watt power, the pascal pressure).

Correct Answer: Meter

The SI unit of length is the meter: it is the base unit from which kilometres, centimetres and millimetres are derived (the litre is volume, the gram mass, the second time).

Correct Answer: Acoustics

The study of sound is called acoustics: it covers how sound is produced, transmitted and heard, from musical instruments to ultrasound (optics covers light, mechanics covers motion and forces).

Correct Answer: Isaac Newton

Isaac Newton discovered gravity: his law of universal gravitation (1687) explained why apples fall and planets orbit, while Einstein later reframed gravity as the curvature of spacetime and Galileo studied falling bodies.

Correct Answer: Telescope

A telescope is used to see distant objects in space: it gathers light from stars, planets and galaxies too faint or far for the naked eye (a microscope magnifies tiny nearby objects, a periscope looks around obstacles).

Correct Answer: Manometer

A manometer measures the pressure of gases: it compares a gas's pressure against a liquid column, while a barometer measures atmospheric pressure, an altimeter measures height, and a speedometer measures speed.

Correct Answer: Newton

Newton gave the three laws of motion: published in the Principia (1687), they describe inertia, force as mass times acceleration, and equal and opposite reactions (Einstein gave relativity, Galileo studied falling bodies, Archimedes worked on buoyancy).