P1.2 - Energy and Efficiency

Question 1

What are the different types of energy?

Answer 1

Electrical energy

Light energy

Sound energy

Kinetic energy

Thermal energy

Gravitational potential energy

Elastic potential energy

Chemical energy

Magnetic energy

Question 2

What is an example of electrical energy?

Answer 2

Whenever a current flows

Question 3

What is an example of light energy?

Answer 3

From the Sun, lights, etc

Question 4

What is an example of sound energy?

Answer 4

Energy released from vibrating objects (noise)

Question 5

What is an example of kinetic energy?

Answer 5

From movement

Question 6

What is an example of thermal energy?

Answer 6

Heat energy that flows from hot to cold objects

Question 7

What is an example of gravitational potential energy?

Answer 7

Possessed by falling objects

Question 8

What is an example of elastic potential energy?

Answer 8

Stretched springs, elastic, etc

Question 9

What is an example of nuclear energy?

Answer 9

Released from nuclear reactions

Question 10

What is an example of magnetic energy?

Answer 10

In magnets, etc

Question 11

What are gravitational, elastic, and chemical energy examples of?

Answer 11

They are all stored - they are waiting to be turned into other forms of energy.

Question 12

What is the conservation of energy?

Answer 12

Energy can be transferred usefully from one form to another. It can be stored or dissipated - but it cannot be created or destroyed.

Question 13

When is energy useful?

Answer 13

Energy is only useful when it can be converted from one form to another.

Question 14

What are some examples of energy transfer?

Answer 14

Batteries: Chemical energy into Electrical and heat energy

Potential energy (firing a projectile): Elastic into kinetic and heat energy.

Question 15

Describe what happens in an energy transfer in terms of useful energy.

Answer 15

When useful devices transform energy from one form to another, some of the useful energy is wasted as heat.

Question 16

When is a device more efficient?

Answer 16

A more efficient device will waste less energy.

Question 17

What is a machine?

Answer 17

A machine is a device that turns one type of energy into another.

Question 18

What is the equation for efficiency?

Answer 18

Efficiency = Useful energy or power out/Total energy or power in

Times this by 100 to get it as a percentage.

Question 19

Why is no device 100% efficient?

Answer 19

The wasted energy is usually spread out as heat.

Question 20

Why are heaters 100% efficient?

Answer 20

All the energy (wasted or useful) will be useful heat energy.

Question 21

Describe what happens to wasted energy.

Answer 21

Wasted energy is eventually transferred to the surroundings, which become warmer.

The wasted energy becomes less concentrated and more spread out.

It becomes less useful.

Question 22

Describe how the choices in light bulbs can differ.

Answer 22

Energy saving bulbs are more cost-effective than ordinary bulbs.

A low-energy bulb is about as 4 times efficient as an ordinary light bulb.

LEDs are more efficient than low energy bulbs and can last longer. However, they are more expensive and do not emit as much light as conventional lights.

Question 23

How do you work out if an appliance is cost effective?

Answer 23

Work out its payback time.

Question 24

What do heat exchangers do?

Answer 24

They reduce the quantity of wasted heat energy that is list.

Question 25

How do heat exchangers work?

Answer 25

They pump a cool fluid through the escaping heat.

The temperature rises as it gains heat energy.

This heat energy in the fluid can be converted into useful energy.

Question 26

What are sankey diagrams?

Answer 26

They can show us an easy way to check how much energy is being usefully employed compared to the amount being wasted.

The thicker the arrow, the more energy.