Question

Two fuse wires of the same length are rated 5 A and 20 A.Which of the fuse wires is thicker and why ?

• A. 5 A
• B. 20 A
• C. Both have same thickness
• D. Cannot be same

Answer 1

Answer: (B)

20 A

The resistance of a given length of flat fuse wire is inversely proportional to it`s thickness. Therefore increasing the thickness of a given fuse wire lowers the fuse resistance and thereby increases the amount of current the fuse can carry without generating enough heat to burn the fuse open.
Hence,among two fuse wires of the same length rated 5 A and 20 A,a higher rated fuse (i.e., 20 A fuse) will be thicker.