Physics - Definitions

Question 1

Define heat capacity

Answer 1

It is the amount of heat required to raise temperature of a substance by 1°C.

Unit: J/K

Question 2

Define heat.

Answer 2

Heat is a form of energy that can be transferred from hotter substance to a colder substance, the energy being in the form of kinetic energy of the molecules of the substance.

Question 3

Define diffusion.

Answer 3

Movement of substance from an area of higher concentration to lower concentration, resulting from spontaneous movement of its constituent particles.

Question 4

Osmosis

Answer 4

Migration of solvents from solution of lower concentration to higher concentration when they are separated by a semi permeable membrane.

Question 5

State Henry’s law.

Answer 5

At a particular temperature, the amount of a given gas dissolved in a given liquid is directly proportional to partial pressure of the gas in equilibrium with the liquid.

It describes the mechanism of narcosis by Nitrogen, Oxygen etc. gases.

All gases have narcosis potency except Helium hence used as heliox during diving.

Question 6

Humidity

Answer 6

Amount of water vapor present in a gas or in the atmosphere.

Question 7

Absolute humidity

Answer 7

It is the mass of water vapor present in a given volume of air.

Expressed as gm/m3 or mg/Litre

Question 8

Relative humidity

Answer 8

It is the ratio of mass of water vapor present in a given volume of air and mass required to saturate that given volume of air at the same temperature.

RH= Mp/Ms

Question 9

Define Temperature

Answer 9

Temperature is the thermal state of a substance which determines wheter it will give heat to another substance or receive heat from it, heat being transferred from substance at the higher temperature to the lower temperature.

Question 10

Define solubility

Answer 10

Extent to which a substance dissolves in another substance.

Question 11

Dalton’s law

Answer 11

In a mixture of gases, the pressure exerted by each gas is the same as that as it would exert if it alone occupied the container.

By John Dalton

In 1891

Question 12

Charles’ law

Answer 12

At constant pressure,
the volume of a given mass of gas varies directly with absolute temperature.

By Tachques Charles

In 1787

Question 13

Boyle’s law

Answer 13

At constant temperature,
volume of a given mass of gas varies inversely with the absolute pressure.

By Robert Boyle

In 1662

Question 14

Exponential

Answer 14

At a given time, the rate of change quality of a process is proportional to quantity of that process.

Question 15

Flow

Answer 15

Flow is defined as the quantity of a fluid passing a point in unit time.

F= Q/t

Question 16

Force

Answer 16

Force is that which changes or tends to change the state of rest or motion of an object

SI unit: Newton

1 Newton is the force that will give a mass of 1 kg acceleration of 1 m/s2

Question 17

Pressure

Answer 17

It is the force applied or distributed over a surface or area.

P= f/a

SI Unit: Pascal

Question 18

Pascal

Answer 18

1 pascal is a pressure of 1 Newton acting over an area of 1 square meter.

Question 19

Mole

Answer 19

1 mole is defined as 12gm of Carbon-12 containing 6.02 × 10 to the power 23 atoms.

Number of mole = mass of substance / molar mass

Question 20

Molar mass

Answer 20

Mass of 1 mole of the substance

Measured in gm/mol

Question 21

Specific heat capacity

Answer 21

It is the energy required to raise the temperature of 1 kg of a substance by 1 K.

Heat capacity = mass × specific heat capacity

Question 22

Latent heat

Answer 22

Energy released of absorbed when a substance undergoes a change of state without a change in it’s temperature.

Question 23

Specific latent heat

Answer 23

Defined as the heat required to convert 1 kg of substance from 1 phase to another a constant temperature.

Question 24

Humidity

Answer 24

Amount of water vapor present in a gas or in the atmosphere.