Mains Electricity
4 marks · EasyA student wants to use an electric kettle (rated at 1500 W) on a 230 V mains supply. She checks the plug, which is fitted with a 5 A fuse.
Calculate the current taken by the kettle when it is switched on.
Explain whether a 5 A fuse is suitable for this kettle.
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.
Show answer
(a) I = 6.52 A (or 6.5 A) A · must show P = IV calculation
(b) No, a 5 A fuse is not suitable because the kettle needs more than 5 A to operate so the fuse would blow. A 7 A or 13 A fuse would be suitable. · must show 5 A too low, Needs higher rated fuse
Show mark scheme and worked solution
Marking points
M1 (a) · 1 mark · States and correctly rearranges P = IV.
A1 (a) · 1 mark · Calculates current I = 1500 / 230 = 6.52 A.
B1 (b) · 1 mark · States 5 A fuse is too small/unsuitable.
B2 (b) · 1 mark · Suggests correct higher fuse (7 A or 13 A, or similar).
Worked solution
a) Use P = IV, so I = P / V = 1500 W / 230 V = 6.52 A.
b) The kettle draws more than 5 A, so the 5 A fuse would blow. A fuse just above 6.5 A, such as a 7 A or 13 A fuse, is suitable.