# How to Determine the Diameter of a Fuse Wire

## What is a fuse in an electric circuit?

A fuse in an electric circuit is a wire that is designed to melt, and thereby open the circuit, if the current exceeds a predetermined value.

## What current density will cause the fuse material to melt?

The fuse material will melt when the current density rises to 480 A/cm².

## How can we calculate the diameter of a cylindrical wire for a fuse?

To calculate the diameter of a cylindrical wire for a fuse, we need to know the current flowing through the fuse and the current density at which the fuse material will melt.

## Answer:

The diameter of the cylindrical wire should be 44.6 mm to limit the current to 0.75 A.

When dealing with fuses in electric circuits, it's crucial to ensure that the wire diameter is appropriate to handle the current without exceeding the predetermined value that would cause the fuse to melt.

In this scenario, where the current density at which the fuse material melts is 480 A/cm² and the current to be limited is 0.75 A, the diameter of the cylindrical wire can be calculated using the formula for the area of a cylindrical wire:

**Area of the cylindrical wire = Current / Current density**

By substituting the given values into the formula, we find that the diameter of the wire should be 44.6 mm to ensure that the current is limited to 0.75 A and the fuse does not melt prematurely.

Therefore, it's essential to calculate the diameter of the fuse wire accurately to maintain the safety and functionality of the electric circuit.