HPQ:Physics:KS4:Energy efficiency:Camilla Leslie

Question

If a new hairdryer is more efficient than your old one

Which statement/s is/are correct?

A It takes in more energy than it gives out

B It costs less to buy but works just as well

C It gives out more energy than it takes in

D it wastes less energy

E it dries your hair more quickly

Answer

The answer is D

The students who got this answer alone would more on to more challenging work and all other answer combinations would lead the students to do some further work on efficiency and energy conservation.  I would then group the students so each group had to explain why e.g. Response A is incorrect etc.

 


Comments

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Sergio Fabbri

Useful HPQ, Camilla. I think it helps to focus on the correct concept of energy balance then just reasoning in terms of partial performance (what the tool makes and nothing else). Thank you. 

Sergio F.

Adam Little

Thank you for adding this.  Efficiency is an area students really struggle with and building up a bank of decent questions like this, that people can share are very useful.