Question

Statement I: Fuse wire must have high resistance and low melting point.
Statement II: Fuse is used for small current flow only.

• A. If both statements are true and statement II is the correct explanation of statement I.
• B. If both statements are true but statement II is not the correct explanation of statement $I$.
• C. If statement $I$ is true but statement II is false.
• D. If both statements are false.

Answer 1

Answer: (C)

Fuse wire must have high fesistance because in series current remains same. Also, according to jonle's law, $H=\frac{i^{2}Rt}{4.2}$, therefore heat produced is high if $R$ is high. The melting point must be low so that the wire may melt with increase in temperature. As the current greater than maximum safe value flows through the fuse wire, it heats up, melts and break the circuit.