An electric kettle (1500 W, 220 V) is protected by a 5 A fuse in the live wire and…
PHYSICS · Single correct · CBSE · Physics · Magnetic Effects of Electric Current · Magnetic Effects of Electric Current
Problem
An electric kettle (1500 W, 220 V) is protected by a 5 A fuse in the live wire and its metal body is earthed through a resistance of 0.5 Ω. Suppose the live conductor accidentally touches the metal body. Which one of the following correctly describes what happens immediately after the fault?
(a) A current of approximately 5A flows through the earth path; this is within the fuse rating so the fuse does not blow and the body stays live.
(b) A current of approximately 6.8A flows through the earth path; being only slightly above the fuse rating, the fuse survives and the kettle continues to operate.
(c) A current of approximately 4.4×102A flows through the earth path; the resulting large current melts the 5 A fuse almost instantaneously and disconnects the supply.
(d) No current flows because the earth connection fixes the body at zero potential, so the fuse remains intact and the kettle is safe.