Energy Transfer By Heating

Question 0

The hotter the object…?

Answer 0

The more infra red radiation it emits.

Question 1

What is Infra red radiation part of?

Answer 1

It is part of the electromagnetic spectrum and can travel in a vacuum.

Question 2

How is infra red detected?

Answer 2

1. Thermometer
2. Sensors
3. Infra red cameras

Question 3

Light shiny surfaces are best at…?

Answer 3

Reflecting infra red

Question 4

Dark matt surfaces are best at…?

Answer 4

Absorbing and emitting infra red

Question 5

Solids

Answer 5

• particles are next to each other in fixed positions
• they vibrate about their fixed positions
• the forces between them are strong

Question 6

Liquids

Answer 6

• particles move at random and are in contact with each other
• a liquid doesn’t have its own shape and can flow
• forces are weaker than solids

Question 7

Gases

Answer 7

• particles move randomly and are further apart which means the density of the gas is less than a solid or liquid
• the particles have a lot more energy
• forces between them are very small

Question 8

How can a substance change from one state to another?

Answer 8

By heating or cooling

Question 9

What is a good conductor?

Answer 9

Metal

Question 10

What is a bad conductor?

Answer 10

Insulators

Question 11

What are fluids?

Answer 11

Liquids and gases

Question 12

What does convection do?

Answer 12

Heat energy is transferred from hot places to cooler places by convection.

Question 13

What don fluids do when they are heated?

Answer 13

They expand

Question 14

How does a liquid evaporate?

Answer 14

When it’s molecules escape into the surrounding air

Question 15

What happens when water condenses on glass?

Answer 15

Water molecules in the air form a liquid on the glass.

Question 16

What happens when a liquid evaporates?

Answer 16

It looses it’s faster-moving molecules and it cools.

Question 17

How can evaporation be increases?

Answer 17

The surface area

Question 18

What does the rate of energy transfer depend on?

Answer 18

The SHAPE, SIZE and TYPE.
The materials the object is in contact with.

The TEMPERATURE and DIFFERENCE between the object and it’s surroundings.

Question 19

As Electronic components can stop working if they over heat what is one way to prevent this.

Answer 19

They are fixed to metal plates to keep them cool.

Question 20

What and why is loft insulation made up of what it is?

Answer 20

Fibreglass because it reduces the rate of energy transfer through the roof because it is a good insulator.

Question 21

How are solar panels designed to suit their purpose?

Answer 21

They are matt black to absorb heat.

Question 22

Plastic is a good conductor true/false?

Answer 22

False

Question 23

Why are metals good conductors?

Answer 23

Metals are the best conductors of heat because they have free electrons which diffuse (spread out) and collide with other free electrons and ions. In this way they transfer kinetic energy.

Question 24

Why is fibreglass a good insulator?

Answer 24

They are poor conductors because they have no free electrons

Question 25

Convection?

Answer 25

A convection current is created when hot, less dense fluid rises and cold, denser fluid sinks

Question 26

Evaporation?

Answer 26

Evaporation is when a liquid is turned into a gas and can be increased by increasing the surface area of the liquid, increasing the temperature or by creating a draught of air

Question 27

What causes cooling?

Answer 27

This is due to the fast moving molecules that escape the liquid, this results in the kinetic energy decreasing.

Question 28

What is condensation?

Answer 28

Condensation is when a gas turns into a liquid.

Question 29

What do U Values do?

Answer 29

‘U-values’ tell us how much energy per second per m2 passes through different materials. The lower the U-value, the better the insulator

Question 30

Why are solar panels expensive?

Answer 30

Because use solar radiation to heat water.