Fuse wire is a wire of

• (A) High resistance and high melting point
• (B) High resistance and low melting point
• (C) Low resistance and low melting point
• (D) Low resistance and high melting point

To determine the correct characteristics of fuse wire, let's break down the options and understand the purpose of a fuse in an electrical circuit. A fuse is designed to protect electrical circuits by melting and breaking the circuit when the current exceeds a certain level, preventing overheating and potential fires.

Characteristics of Fuse Wire

Fuse wires are specifically made to have certain properties that allow them to function effectively in this protective role. The key characteristics we need to consider are resistance and melting point.

Resistance

Fuse wires typically have low resistance. This is important because a low resistance allows normal current to flow through the wire without significant energy loss. If the resistance were high, the fuse would heat up and potentially melt under normal operating conditions, which would defeat its purpose.

Melting Point

On the other hand, fuse wires are designed to have a low melting point. This is crucial because when the current exceeds the safe limit, the wire needs to melt quickly to break the circuit and prevent damage. A high melting point would mean that the fuse would not react in time to protect the circuit.

Evaluating the Options

• (A) High resistance and high melting point: This would not be effective for a fuse, as it would not melt under normal conditions.
• (B) High resistance and low melting point: While the low melting point is correct, high resistance is not suitable for a fuse.
• (C) Low resistance and low melting point: This is the ideal combination for a fuse wire, allowing it to operate effectively.
• (D) Low resistance and high melting point: The low resistance is good, but the high melting point would prevent it from functioning properly.

The Correct Answer

Based on this analysis, the correct answer is (C) Low resistance and low melting point. This combination allows the fuse wire to carry current safely under normal conditions while ensuring it will melt and break the circuit when the current exceeds safe levels.

Real-World Example

Think of a fuse wire like a safety valve in a pressure cooker. Just as the valve releases steam to prevent the cooker from exploding when pressure gets too high, the fuse wire melts to stop the flow of electricity when the current becomes too high. Both are designed to protect the system from damage.

In summary, the properties of low resistance and low melting point are essential for fuse wires to perform their protective function effectively in electrical circuits.