Efficiency

Question 1

What is efficiency?

Answer 1

• Amount of useful energy

Question 2

When are useful devices useful?

Answer 2

• They transfer energy from one store to another

Question 3

When is input energy wasted?

Answer 3

• Transferred to a useless energy store

- Thermal energy store

Question 4

Formulae for efficiency:

Answer 4

Useful output energy transfer / Total input energy transfer

Useful power output / Total power input

Question 5

Why is any device 100% efficient?

Answer 5

• They’ll always be energy transferred to useless store

Question 6

What device is 100% efficient and why?

Answer 6

• Electric heaters

- All energy in electrostatic energy store transferred to “useful” thermal energy store