Famous Theories

Question 1

The total current entering a junction equals the total current leaving it.

Answer 1

Kirchhoff’s Current Law (KCL)

Question 2

The sum of voltages around a closed loop is zero.

Answer 2

Kirchhoff’s Voltage Law (KVL)

Question 3

The direction of an induced current opposes the change in magnetic flux that caused it.

Answer 3

Lenz’s Law

Question 4

A changing magnetic field induces an electromotive force (EMF) in a conductor.

Answer 4

Faraday’s Law of Electromagnetic Induction

Question 5

The electrostatic force between two charges is directly proportional to the product of their magnitudes and inversely proportional to the square of the distance between them.

Answer 5

Coulomb’s Law

Question 6

Voltage (V) = Current (I) × Resistance (R)

Answer 6

Ohm’s Law

Question 7

Energy cannot be created or destroyed, only transferred or converted.

Answer 7

First Law of Thermodynamics

Question 8

Heat flows from hot to cold, and entropy (disorder) always increases in an isolated system.

Answer 8

Second Law of Thermodynamics

Question 9

As temperature approaches absolute zero, the entropy of a perfect crystal approaches zero.

Answer 9

Third Law of Thermodynamics

Question 10

If two systems are in thermal equilibrium with a third system, they are in equilibrium with each other.

Answer 10

Zeroth Law of Thermodynamics

Question 11

An object remains in motion or at rest unless acted upon by an external force (Inertia).

Answer 11

Newton’s First Law of Motion

Question 12

Force = Mass × Acceleration (F = ma).

Answer 12

Newton’s Second Law of Motion

Question 13

Every action has an equal and opposite reaction.

Answer 13

Newton’s Third Law of Motion

Question 14

Every mass attracts every other mass with a force proportional to their masses and inversely proportional to the square of the distance between them.

Answer 14

Law of Universal Gravitation

Question 15

The force needed to extend or compress a spring is proportional to the displacement (F = kx).

Answer 15

Hooke’s Law

Question 16

Kirchhoff’s Laws (Name)

Answer 16

Gustav Kirchhoff (1845)

Question 17

Lenz’s Law (Name)

Answer 17

Heinrich Lenz (1834)

Question 18

Faraday’s Laws of Electromagnetic Induction (Name)

Answer 18

Michael Faraday (1831)

Question 19

Coulomb’s Law (Name)

Answer 19

Charles-Augustin de Coulomb (1785)

Question 20

Ohm’s Law (Name)

Answer 20

Georg Ohm (1827)

Question 21

First Law of Thermodynamics

Answer 21

Conservation of Energy

Question 22

Second Law of Thermodynamics

Answer 22

Entropy

Question 23

Third Law of Thermodynamics

Answer 23

Absolute Zero

Question 24

Zeroth Law of Thermodynamics

Answer 24

Thermal Equilibrium

Question 25

Newton’s Laws of Motion (Name)

Answer 25

Isaac Newton (1687)

Question 26

Law of Universal Gravitation (Name)

Answer 26

Isaac Newton (1687)

Question 27

Hooke’s Law

Answer 27

Robert Hooke (1678)

Question 28

Bernoulli’s Principle

Answer 28

Daniel Bernoulli (1738)

Question 29

An increase in the speed of a fluid results in a decrease in pressure or potential energy.

Answer 29

Bernoulli’s Principle

Question 30

Pressure applied to a confined fluid is transmitted equally in all directions.

Answer 30

Pascal's Law

Question 31

A body submerged in a fluid experiences an upward buoyant force equal to the weight of the displaced fluid.

Answer 31

Archimedes’ Principle

Question 32

It describes the bending of light when it passes from one medium to another (refraction).

Answer 32

Snell’s Law

Question 33

Every point on a wavefront acts as a source of new wavelets.

Answer 33

Huygens’ Principle

Question 34

The frequency of a wave changes based on the relative motion between the source and observer.

Answer 34

Doppler Effect

Question 35

Snell's Law (Name)

Answer 35

Willebrord Snellius (1621).

Question 36

Huygens' Principle (Name)

Answer 36

Christiaan Huygens (1678)

Question 37

Doppler Effect (Name)

Answer 37

Christian Doppler (1842)

Question 38

The total enthalpy change of a reaction is the same, regardless of the reaction pathway.

Answer 38

Hess’s Law – Germain Hess (1840)

Question 39

At constant pressure, the volume of a gas is directly proportional to its temperature (V ∝ T).

Answer 39

Charles’s Law – Jacques Charles (1787)

Question 40

At constant temperature, pressure and volume of a gas are inversely proportional (P ∝ 1/V).

Answer 40

Boyle’s Law – Robert Boyle (1662)

Question 41

Energy cannot be created or destroyed, only transferred or converted.

Answer 41

Law of Conservation of Energy – First Law of Thermodynamics

Question 42

Matter cannot be created or destroyed in a chemical reaction.

Answer 42

Law of Conservation of Mass – Antoine Lavoisier (1789)

Question 43

When a system at equilibrium is disturbed, it shifts to counteract the change.

Answer 43

Le Chatelier’s Principle – Henry Le Chatelier (1884)

Question 44

Atoms are indivisible, combine in whole-number ratios, and retain identity in chemical reactions.

Answer 44

Dalton’s Atomic Theory – John Dalton (1803)

Question 45

PV = nRT (Pressure × Volume = Moles × Gas Constant × Temperature).

Answer 45

Ideal Gas Law – Boyle, Charles, and Avogadro’s work combined

Question 46

Equal volumes of gases at the same temperature and pressure contain the same number of molecules.

Answer 46

Avogadro’s Law – Amedeo Avogadro (1811)

Question 47

If two elements form more than one compound, their mass ratios are simple whole numbers.

Answer 47

Law of Multiple Proportions – John Dalton (1803)

Question 48

The properties of elements repeat periodically when arranged by atomic number.

Answer 48

Periodic Law – Dmitri Mendeleev (1869)