Explanation:
An electric fuse wire is a safety device that is used to protect electrical circuits from excessive current. When the amount of current flowing through the fuse wire exceeds its maximum rating, the wire melts and breaks the circuit, thus preventing any damage to the electrical equipment or potential danger to the users.

Why does the electric fuse wire melt?
The electric fuse wire is typically made of a material with a low melting point, such as tin, lead, or an alloy. When the current passing through the fuse wire exceeds its maximum rating, the wire heats up due to the electrical resistance it offers. This increase in temperature eventually reaches the melting point of the fuse wire, causing it to melt and break the circuit.

The purpose of the electric fuse wire:
The main purpose of the electric fuse wire is to protect the electrical circuit and the connected devices from the excessive flow of current, which can lead to overheating, damage, or even fire hazards. By melting and breaking the circuit, the fuse wire interrupts the flow of current and prevents any further damage.

Why is the correct answer option 'B' - more than a maximum amount?
The correct answer is option 'B' - more than a maximum amount. This means that the electric fuse wire will melt if the amount of current flowing through it exceeds its maximum rating. It is important to note that the maximum rating of the fuse wire is determined based on the electrical circuit's capacity and the connected devices' requirements.

Consequences of not using a fuse wire or using a wrong rating:
If a fuse wire is not used or if a fuse wire with a higher rating is used, the excessive amount of current flowing through the circuit can cause overheating, damage to the electrical equipment, or even electrical fires. On the other hand, if a fuse wire with a lower rating is used, it may constantly melt and break the circuit, resulting in frequent power interruptions and inconvenience.

Advantages of using a fuse wire:
- Protection: The fuse wire provides protection against excessive current flow, preventing damage to electrical equipment and potential hazards.
- Easy replacement: When a fuse wire melts, it is easy to replace with a new one, restoring the circuit's functionality.
- Cost-effective: Fuse wires are affordable and readily available, making them a cost-effective solution for electrical circuit protection.

In conclusion, an electric fuse wire melts if the amount of current flowing through it is more than its maximum rating. This melting of the fuse wire protects the electrical circuit and connected devices from damage and potential dangers. It is crucial to use the correct rating of fuse wire to ensure effective protection and prevent any adverse consequences.