A fuse wire with a circular cross-sectional radius of 0.02 mm blows with a current of 5 ampere. For what current, another fuse wire made from the same material with cross-sectional radius of 0.04 m wiII blow ?
We know that the safe current for a fuse
where r is the radius of fuse wire.
i1 = 5amp.,r1 = 0.02mm and r2 = 0.04mm
or