This GCSE Physics quiz on energy looks at transfers and efficiency. The principle of conservation of energy states that 'energy can neither be created nor destroyed, only changed from one form into another'. Energy changes make the world work. Plants transfer the light energy from the Sun into chemical energy of food by photosynthesis. Animals, including humans, change the chemical energy of food into heat and kinetic energy. We transfer the chemical energy stored in coal, oil and gas into electrical energy to run our electronic appliances and machines; into kinetic energy to run our vehicles; into heat energy to cook our food and more.
The electrical energy generated at power stations is transferred into other forms of energy by our machines and electronic devices.
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Once transferred into other forms, energy then becomes more difficult for us to use, it is then called wasted energy. An example of this is a car engine running on petrol. An engine converts the chemical energy of its fuel into heat energy by burning. The gases created by burning the fuel have a larger volume than the fuel itself, this fact is used to create kinetic energy as these gases cause the pistons to move. This kinetic energy is then used to drive the wheels round. Only about 30 percent of the energy contained in the original petrol is actually transferred into kinetic energy that moves the car, the rest is wasted as heat, sound and light energy and simply disperses into the air. Diesel engines are slightly better at transferring energy, up to 40 percent ends up as useful kinetic energy.
The amount of energy that is transferred by something is called the efficiency. It can be calculated as a percentage by dividing the amount of useful energy transferred by the original amount of energy available. It is then converted into a percentage by multiplying by one hundred. This efficiency can be calculated using either energy or power. Using more efficient devices will reduce the amount of energy wasted which will benefit the whole world.
We talk of energy being renewable or non-renewable. As science has progressed, humans have begun to realise that our supplies of chemical energy won't last forever. Once they are gone, we will have to wait for tens of millions of years for them to be re-formed so we need to regard these as being non-renewable. Scientists and engineers are therefore trying to find ways of using other sources of energy ~ for example, the wind, waves and tides, the heat of the earth and energy from the Sun. We call these renewable energies because they will always be there, or at least for as long as the Earth exists.
The big problem is that these alternative forms of energy are much less concentrated than the chemical energy of the fossil fuels. This makes them more difficult to use ~ for example, it is said that it could take about 6,000 wind turbines spread out over 250,000 acres to replace one power station. Some of these could be built out at sea but this then brings other problems.
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1.
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What can be done to energy? |
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[ ] |
It can be transferred |
[ ] |
It can be stored |
[ ] |
It can be dissipated |
[ ] |
All of the above |
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2.
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What cannot be done to energy? |
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[ ] |
Created or destroyed |
[ ] |
Dissipated |
[ ] |
Transferred |
[ ] |
Stored |
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3.
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During an energy transfer, only part of it may be usefully transferred. What happens to the remainder of the unused energy? |
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[ ] |
It's wasted |
[ ] |
All the energy is all transferred and used successfully |
[ ] |
It is converted into carbon |
[ ] |
It becomes a gas |
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4.
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What happens to wasted energy? |
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It decomposes into the ground |
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It becomes hot |
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No energy is ever wasted |
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It is transferred into its surroundings |
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5.
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Which formula can be used to calculate the percentage of energy transferred by a device? |
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[ ] |
Energy Transferred = Useful Energy Output⁄Total Energy Input x 100 |
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Energy Transferred = Total Energy Input⁄Useful energy output x 100 |
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Energy Transferred = Useful Energy Output⁄Total Energy Input x 10 |
[ ] |
Energy Transferred = Total Energy Input⁄Useful energy output x 10 |
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6.
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Which formula can be used to calculate the percentage of power transferred by a device? |
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Power Transferred = Useful Power Output⁄Total Power Input x 100 |
[ ] |
Power Transferred = Total Power Input⁄Useful Power Output x 100 |
[ ] |
Power Transferred = Useful Power Output⁄Total Power Input x 10 |
[ ] |
Power Transferred = Total Power Input⁄Useful Power Output x 10 |
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7.
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Calculate the efficiency of a heater which can convert 700 joules of chemical energy into 175 joules of heat energy. |
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[ ] |
10% |
[ ] |
25% |
[ ] |
35% |
[ ] |
50% |
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8.
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A wind turbine generates 100 joules of electricity from a gust of wind which has 300 joules of energy. How efficient is the turbine? |
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[ ] |
10% |
[ ] |
33% |
[ ] |
50% |
[ ] |
66% |
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9.
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A solar panel is 20% efficient at converting light energy into electricity. If it generates 200 joules of electrical power, how much power is wasted? |
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[ ] |
500 J |
[ ] |
750 J |
[ ] |
800 J |
[ ] |
1000 J |
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10.
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An LED converts around 80% of the energy supplied to it into light. How much energy is converted into light if a total of 50 J is supplied to it? |
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[ ] |
30 J |
[ ] |
40 J |
[ ] |
50 J |
[ ] |
60 J |
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1.
|
What can be done to energy? |
|
[ ] |
It can be transferred |
[ ] |
It can be stored |
[ ] |
It can be dissipated |
[x] |
All of the above |
|
|
2.
|
What cannot be done to energy? |
|
[x] |
Created or destroyed |
[ ] |
Dissipated |
[ ] |
Transferred |
[ ] |
Stored |
|
|
3.
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During an energy transfer, only part of it may be usefully transferred. What happens to the remainder of the unused energy? |
|
[x] |
It's wasted |
[ ] |
All the energy is all transferred and used successfully |
[ ] |
It is converted into carbon |
[ ] |
It becomes a gas |
|
|
4.
|
What happens to wasted energy? |
|
[ ] |
It decomposes into the ground |
[ ] |
It becomes hot |
[ ] |
No energy is ever wasted |
[x] |
It is transferred into its surroundings |
|
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5.
|
Which formula can be used to calculate the percentage of energy transferred by a device? |
|
[x] |
Energy Transferred = Useful Energy Output⁄Total Energy Input x 100 |
[ ] |
Energy Transferred = Total Energy Input⁄Useful energy output x 100 |
[ ] |
Energy Transferred = Useful Energy Output⁄Total Energy Input x 10 |
[ ] |
Energy Transferred = Total Energy Input⁄Useful energy output x 10 |
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6.
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Which formula can be used to calculate the percentage of power transferred by a device? |
|
[x] |
Power Transferred = Useful Power Output⁄Total Power Input x 100 |
[ ] |
Power Transferred = Total Power Input⁄Useful Power Output x 100 |
[ ] |
Power Transferred = Useful Power Output⁄Total Power Input x 10 |
[ ] |
Power Transferred = Total Power Input⁄Useful Power Output x 10 |
|
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7.
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Calculate the efficiency of a heater which can convert 700 joules of chemical energy into 175 joules of heat energy. |
|
[ ] |
10% |
[x] |
25% |
[ ] |
35% |
[ ] |
50% |
|
|
8.
|
A wind turbine generates 100 joules of electricity from a gust of wind which has 300 joules of energy. How efficient is the turbine? |
|
[ ] |
10% |
[x] |
33% |
[ ] |
50% |
[ ] |
66% |
|
|
9.
|
A solar panel is 20% efficient at converting light energy into electricity. If it generates 200 joules of electrical power, how much power is wasted? |
|
[ ] |
500 J |
[ ] |
750 J |
[x] |
800 J |
[ ] |
1000 J |
|
|
10.
|
An LED converts around 80% of the energy supplied to it into light. How much energy is converted into light if a total of 50 J is supplied to it? |
|
[ ] |
30 J |
[x] |
40 J |
[ ] |
50 J |
[ ] |
60 J |
|
|