Physics: Equations, Eponymous Laws and SI Units

Question 1

Boyle’s Law

Answer 1

P∝1/V i.e. P1V1 = P2V2

Pressure is inversely proportional to volume

Question 2

Charles’ Law

Answer 2

V∝T i.e. V1/T1 = T2/V2

Volume is proportional to temperature

Question 3

Gay-Lussac Law

Answer 3

P∝T i.e. P1/T1 = P2/T2

Pressure is proportional to temperature

Question 4

Avogadro’s Law

Answer 4

Equal volumes of all gases, at the same temperature and pressure, have the same number of molecules

i.e. V ∝ n

Question 5

Molar Volume

Answer 5

22.41 litres/mol at standard temperature and pressure (273.15K i.e. 0°C and 101.325kPa i.e. 1 atm)

Question 6

Ideal Gas Equation

Answer 6

PV = nRT, where R is the Boltzmann constant

Question 7

Henry’s Law

Answer 7

At constant pressure, amount of gas dissolved in a solvent is proportional to the partial pressure above the solvent

Question 8

Dalton’s Law

Answer 8

The partial pressure of a fixed mass of gas in a mixture of gasses is the same as the pressure it would exert alone

Question 9

Hysteresis

Answer 9

The dependence of the state of a system on its history i.e. a measurement differs depending on whether the value is rising or falling.

Question 10

SI unit of time

Answer 10

Second (s) - one second = 9,192,631,770 oscillations of a Caesium-133 atomic clock.

Question 11

SI unit of distance

Answer 11

Metre (m) - One metre = The distance travelled by light in vacuum in 1/299,792,458 second

Question 12

SI unit of amount of substance

Answer 12

Mole (mol) - One Mole = The amount of substance containing the same number of atoms/molecules as there are atoms in 12g of Carbon-12

Question 13

SI unit of current

Answer 13

Ampere (A) - One Ampere = The current applied to two parallel conductors of negligible cross section and infinite length, one metre apart in a vacuum which would produce a force between them of 2.0 x 10-7 Newtons per metre.

Question 14

SI measure of luminous intensity

Answer 14

Candela (cd) - One Candela = The luminous intensity, in a given direction, of a source that emits monochromatic radiation of frequency 5.4×1014 Hertz and that has a radiant intensity in that direction of 1/683 watt per square radian

Question 15

SI measure of mass

Answer 15

Kilogram (kg) - One Kilogram = The mass of the international kilogram prototype in Pavillon de Breteuil, Sévres, France.

Question 16

SI measure of temperature

Answer 16

Kelvin (K) - One Kelvin = 1/273.16 of the thermal energy of the triple point of water.

Question 17

Heat - definition

Answer 17

Type of energy that moves between two objects due to a difference in temperature

Question 18

Temperature - definition

Answer 18

A measurement of the average kinetic energy of a particles in a system.

OR

Property of an object which determines if heat energy will flow to or from it from another object

Question 19

Absolute zero

Answer 19

Absolute zero is defined as the temperature at which all molecular movement stops

Question 20

Specific heat capacity

Answer 20

The amount of heat energy required to increase one Kg of a substance by one Degree Centigrade/Kelvin

Question 21

Beer’s Law

Answer 21

The absorption of radiation as it passes through a substance increases exponentially as the concentration of the substance increases

Question 22

Lambert’s Law

Answer 22

The absorption of radiation as it passes through a substance increases exponentially as the distance it travels through the substance increases

Question 23

Beer-Lambert Law

Answer 23

Intensity of emergent light = Intensity of incident light x e^-(Distance light travel through substance x concentration of substance x ε - molar absorption coefficient)

I = Io x e^-DCε