The current capacity of a fuse wire does not depend

Correct option is A

The correct answer is (a) on the length of wire

Explanation:
• The core current rating (or melting capacity) of an electrical fuse wire strictly does not depend on its length.
• Under steady-state conditions, the rate of heat generated per unit length equals the rate of heat strictly lost per unit length to the surroundings. Since length cancels out algebraically on both sides of the thermal equilibrium equation, length is irrelevant to the melting current threshold.

Information Booster:
• A fuse is a crucial safety device meant to rigorously break the circuit if excessive current flows. It must possess low melting point and high resistivity.
• According strictly to Preece's law, the fusing current is directly proportional to the radius (or diameter/circumference) raised strictly to the power of 1.5.

Additional Knowledge:
on the circumference of wire (Option b)
• The circumference (radius) heavily determines the cross-sectional area and the surface area for heat dissipation; hence, it absolutely affects the capacity.
on the material of wire (Option c)
• The specific resistivity and melting point strictly depend on the metal/alloy used (e.g., tin-lead alloy), so it dictates capacity.
on the current flowing through it (Option d)
• The very operational premise of a fuse strictly depends on reacting to the magnitude of the current flowing.
None of the above/More than one of the above (Option e)
• Incorrect, as length is exactly the independent variable.

So the correct answer is (a)