Section 4 - Energy Transfers

Question 1

What is the set rule about energy transfers?

Answer 1

No device is 100 percent efficient and the wasted energy is always dissipated as heat.

The entire energy output by machine, both useful and wasted, eventually ends up at heat.

Question 2

Why do we call wasted energy wasted energy?

Answer 2

Because we can’t do anything useful with it.

Question 3

Describe how energy get dissipated.

Answer 3

As the entire energy output ends up at heat, this heat is at first concentrated then it gets transferred to cooler surroundings. Which then becomes warmer. As the heat is transferred to cooler surroundings, the energy becomes less concentrated it dissipates.

Question 4

Link the principle of Conservation of energy to the dissipation of energy.

Answer 4

According to the principle of conservation of energy, the total amount of energy stays the same. So the energy is still there, but it can’t be easily used or collected back in again.

Question 5

Watch out for energy transfer questions in the exam. So remember those patterns below.

Answer 5

Electrical devices convert electrical energy into sound, light, heat, etc. (A bit of wasted heat)

Batteries convert chemical energy to electrical to run electric devices. (A bit of wasted heat)

Gravitational and elastic potential energy always get converted into kinetic energy first. (A bit of wasted heat)

Question 6

What does electricity generation always involve?

Answer 6

Electricity generation always involves converting other forms of energy into electrical energy.