Electricity
5 marks · NormalA hairdryer is labelled '230 V, 1200 W'.
What do these values mean for the operation of the hairdryer?
Calculate the current drawn by the hairdryer during operation.
The hairdryer casing is made of plastic. Explain why this is important for electrical safety.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
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(a) It is designed to use 1200 W of power when plugged into a 230 V supply.
(b) 5.22 A
(c) Plastic is an insulator, so it provides double insulation and protects the user from electric shock.
Show mark scheme and worked solution
Marking points
B1 (a) · 2 marks · Explains correctly what the rating means for both voltage and power.
M1 (b) · 1 mark · Uses correct formula P = I × V and rearranges.
A1 (b) · 1 mark · Correct calculation: I = 1200 / 230 = 5.22 A. (follow-through)
B2 (c) · 1 mark · Explains that plastic casing provides insulation/double insulation for safety.
Worked solution
a. The hairdryer is made to work at 230 V and will use 1200 W of power. This means it should be used with a 230 V mains supply and will consume 1200 J of energy per second.
c. Plastic is an electrical insulator, so it prevents electric shock. The whole casing being plastic means no exposed conductor, so even if there is a fault, it still protects the user (double insulation).