HEAT

Question 1

temperature

Answer 1

the temperature of a body is a measure of how hot it is

Question 2

thermometric property

Answer 2

any measurable property of a body which changes with temperature.

e. g.
- the length of a column of liquid in a tube.
- the resistance of a wire or a thermistor
- the emf of a thermocouple
- the colour of come substances
- the pressure and volume of a fixed mass of gas

Question 3

heat

Answer 3

a form of energy that causes a rise in temperature when added to a body, or a fall in temperature when withdrawn.

Question 4

heat capacity

Answer 4

the heat capacity of a body is the amount of energy needed to raise the temperature of the body by 1K

Question 5

specific heat capacity

Answer 5

the specific heat capacity, c, of a substance is the amount of energy required to raise the temperature of 1kg of the substance by 1K

Question 6

latent heat

Answer 6

the latent heat of a body is the energy required to change the state of the body without changing its temperature.

Question 7

specific latent heat

Answer 7

the specific latent heat, l, of a substance is the amount of energy required to change the state of 1kg of that substance

Question 8

specific latent heat of fusion

Answer 8

the amount of heat energy needed to change 1kg of that substance from a solid to a liquid without a change in temperature

Question 9

specific latent heat of vapourisation

Answer 9

the amount of heat energy needed to change 1kg of that substance from a liquid to a gas without a change in temperature

Question 10

conduction

Answer 10

the movement of heat energy through a substance by the passing on of molecular vibration from molecule to molecule. There is no overall motion of the substance

Question 11

U-Value

Answer 11

the amount of heat energy conducted per second through 1m^2 of that substance when a temperature difference of 1C is maintained between its ends

Question 12

radiation

Answer 12

the transfer of heat energy from one place to another in the form of electromagnetic waves

Question 13

solar constant (solar irradiance)

Answer 13

the average amount of the sun’s energy falling per second perpendicularly on 1 metre squared of the earth’s atmosphere is solar constant. Its value is about 1.35kW m^-2

Question 14

convection

Answer 14

the transfer of heat through a fluid by means of circulating currents of fluid caused by the heat

Question 15

give the equation that defines temperature on the celsius scale

Answer 15

T(˚C) = T (K) -273.15

Question 16

boiling point of water in kelvin

Answer 16

273.15 + 100 = 373.15 K

Question 17

why is necessary to have a standard thermometre?

Answer 17

different thermometre have different thermometric properties at the same temperature

Question 18

principle that underlies the the operation of an electrical storage heater

Answer 18

storage heaters have a large heat capacity. They are heated when electricity is inexpensive (off-peak). They then store a large quantity of energy when they release energy slowly.