Safety devices
4 marks · NormalThe diagram below shows the inside of a UK mains plug.
On the diagram, identify and label the live, neutral, and earth pins, as well as the fuse.
Describe how the fuse protects the user from electric shock.
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) All four items labelled correctly on the diagram. · must show live pin, neutral pin, earth pin, fuse
(b) The fuse melts if too much current flows, breaking the circuit and stopping current, which prevents electric shock. · must show fuse melts or 'blows' if current too high, circuit broken, prevents electric shock
Must show: live pin, neutral pin, earth pin, fuse
Common mistakes: Mixing up live and neutral; Missing fuse label
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · Any two correct labels (live, neutral, earth, fuse)
B2 (a) · 1 mark · All four items correctly labelled
B3 (b) · 1 mark · States that the fuse melts/blows when current is too high
B4 (b) · 1 mark · Explains that melting breaks the circuit, stopping current and protecting user from shock
Worked solution
a) The live pin connects to the right (labelled), the neutral pin to the bottom, the earth pin to the top, and the fuse is shown near the live pin inside the plug.
b) The fuse is a thin wire that melts ('blows') if the current gets too high. Melting the fuse breaks the circuit, so current stops flowing, preventing harm or electric shock to the user.