A fuse wire must be
[amp_mcq option1=”conducting and of low melting point” option2=”conducting and of high melting point” option3=”insulator and of high melting point” option4=”insulator and of low melting point” correct=”option1″]
This question was previously asked in
UPSC NDA-1 – 2019
– 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.