Energy Transfer by Heating Processes

Question 1

What is infrared radiation?

Answer 1

All objects emit and absorb infrared radiation. The hotter an object is the more infrared radiation it radiates in a given time.

Question 2

What surfaces are the best absorbers of infrared radiation?

Answer 2

Dark, matte surfaces. They are also good emitters.

Question 3

What surfaces are the worst absorbers and emitters of infrared radiation?

Answer 3

Light, shiny surfaces

Question 4

What surfaces are good reflectors of infrared radiation?

Answer 4

Light, shiny surfaces

Question 5

What is the use of the kinetic theory?

Answer 5

To explain the different states of matter

Question 6

What state are solids in?

Answer 6

Strong forces of attraction hold the particles together in a fixed and regular arrangement. The particles don’t have much energy so they can only vibrate about their fixed positions.

Question 7

What state are liquids in?

Answer 7

There are weaker forces of attraction between the particles in liquids. The particles are close together, but can move past each other, and form regular arrangements. They have more energy than the particles in a solid- they move in random directions at low speeds.

Question 8

What state are gases in?

Answer 8

There are no forces of attraction between the particles in a gas. The particles have more energy than those in liquids and solids- they are free to move and travel in random directions and at high speeds.

Question 9

What is conduction?

Answer 9

When you heat a solid, you give its particles extra kinetic energy and cause them to vibrate more. The particles collide with their neighbouring particles and pass some of their extra energy onto them, this is called conduction.

Question 10

What does conduction happen faster in denser solids and metals?

Answer 10

Because the particles are closer together in a denser solid and so will collide more often and pass energy between them. Metal contain free electrons that are able to move inside the metal and pass on their extra energy to other electrons and particles in the solid.

Question 11

What is convection?

Answer 11

When the more energetic particles in a liquid or gas move from a hotter region to a cooler region- and take their heat energy with them. Convection cannot happen in solids because because their particles can only vibrate.

Question 12

What is condensation?

Answer 12

When a gas cools, the particles in the gas slow down and lose kinetic energy. The attractive forces between the particles pull them closer together. If the temperature gets cold enough and the gas particles get close enough together that condensation can take place, the gas becomes a liquid.

Question 13

What is evaporation?

Answer 13

It is when particles escape from a liquid and form a gas. Particles can evaporate from a liquid at temperatures that are much lower than the liquid’s boiling point.

Question 14

The rate of evaporation will be faster if:

Answer 14

The temperature is higher
The density of the liquid is lower
The surface area of the liquid is larger

Question 15

The condensation will be faster if:

Answer 15

The temperature of the gas is lower
The temperature of any surface the gas touches is lower
Concentration is higher

Question 16

The rate at which an object transfers energy by heating depends on:

Answer 16

Surface area and volume
The material which the object is made of
The nature of the service which the object is in contact with

Question 17

What is the relationship between the temperature difference of an object and its surroundings and the speed of the energy transfer by heat?

Answer 17

The bigger the temperature difference between the object and its surroundings, the faster the rate at which the energy is transferred by heating

Question 18

What are U-values?

Answer 18

They measure how effective a material is as an insulator. The lower the U-value, the better the material is as an insulator.

Question 19

What can solar panels be used for?

Answer 19

Solar panels may contain water that is heated by radiation from the sun. This water may then be used to heat buildings or provide domestic hot water.

Question 20

What is the specific heat capacity?

Answer 20

The specific heat capacity of a substance is the amount of energy required to change the temperature of 1 kg of the substance by one degree Celsius.