- A fuse wire is designed to protect electrical circuits and appliances from damage due to excessive current. - It is connected in series with the circuit, so it must be able to conduct electricity under normal operating conditions. Thus, it must be conducting. - When the current flowing through the circuit exceeds a specified limit (the fuse rating), the fuse wire heats up due to the Joule effect (heat = I²Rt). - To break the circuit and stop the excessive current flow, the fuse wire must melt when it gets too hot. This requires it to have a low melting point. - If the fuse wire had a high melting point or was an insulator, it would not serve its purpose as a safety device.
A fuse wire must be
Asked in UPSC NDA 1 2019 · Topic: Electric Current (Electrical Power and Energy, Joule heating effect)
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