Changing Energy From One Kind to Another
- Physics
- Ages 8–11 · Grades 3–5
- Hands-on experiment
What you’ll find out
- Machines change energy from one form into another; none of them makes energy.
- Light, sound, movement, heat and electricity are all forms energy can take.
- Some energy always escapes as heat, so no machine is perfect.
No sign-up and no real names. In the lesson you check your understanding as you read, run the experiment yourself, and practise until it sticks.
Machines that change energy
Every machine you use changes energy from one kind into another. A torch turns the energy stored in a battery into light, and a little heat. A wind-up radio turns the movement of your hand into electricity, and the electricity into sound. A solar panel turns sunlight into electricity, which can charge a battery for later. None of these machines makes energy. Each one takes energy that is already there and hands it on in a more useful form.
Nothing is perfect
No machine hands on all the energy it is given. Some always escapes as heat, which is why a phone gets warm while it charges. Old light bulbs were hot to touch, because most of the electricity became heat instead of light. Modern LED bulbs are much better, giving the same light for far less electricity. Scientists say the heat is not lost, because it is still there, warming the room. But it is wasted, because nobody can use it for the job.
Curriculum links: NGSS 4-PS3-4 · NGSS 4-PS3-2