If too high a current flows, the element rises to a higher temperature and either directly melts, or else melts a soldered joint within the fuse, opening the circuit and the current stops flowing through it.

Introduction:
Fuse wire is a thin wire made of a low melting point metal that is used in electric circuits as a safety device. Its purpose is to protect electrical appliances and circuits from high currents, which can lead to damage or even fire hazards. Let's discuss why fuse wire is used in electric circuits and how it prevents electrical appliances and circuits from high current.

Explanation:
1. Purpose of Fuse Wire:
The primary purpose of using a fuse wire in an electric circuit is to protect the electrical appliances and circuit from high currents. It acts as a safety device that breaks the circuit when the current exceeds a certain predetermined level. This helps to prevent damage to the appliances, overheating of wires, and potential fire hazards.

2. How Does a Fuse Wire Work?
When the current flowing through a circuit exceeds the rated value of the fuse wire, the wire heats up due to its resistance. As the wire heats up, it reaches its melting point and melts, breaking the circuit. This discontinuity in the circuit stops the flow of current, preventing it from reaching dangerous levels and protecting the appliances and circuit.

3. Low Melting Point:
Fuse wire is made of a low melting point metal such as lead, tin, or an alloy of these metals. The low melting point ensures that the wire easily melts when the current exceeds its rated value. This is important because the fuse wire needs to break the circuit quickly to prevent any potential damage.

4. Ampere Rating of Fuse Wire:
Fuse wires are available in different ampere ratings, which indicate the maximum current the wire can safely carry. The ampere rating of the fuse wire should be lower than the maximum current capacity of the circuit. This ensures that the fuse wire will melt and break the circuit before the current exceeds the safe limit.

5. Importance of Using Fuse Wire:
By using a fuse wire in an electric circuit, we can protect the electrical appliances and circuit from high currents. This prevents damage to the appliances, reduces the risk of fire hazards, and increases the overall safety of the electrical system. Fuse wires are inexpensive and easy to replace, making them an essential component in electrical circuits.

Conclusion:
In conclusion, fuse wire is used in electric circuits to prevent electrical appliances and circuits from high currents. It works by melting when the current exceeds its rated value, breaking the circuit and stopping the flow of current. By using fuse wires, we can protect our appliances, prevent overheating of wires, and reduce the risk of fire hazards. It is important to choose the correct ampere rating for the fuse wire to ensure its effectiveness in protecting the circuit.