When connected to a mains of 250V, the fuse rating in the plug of an electric device of 1 KW is
A
2 A
B
3 A
C
4 A
D
5 A
Verified Correct Answer: D.
Physical Principles & Numerical Solution
1 KW = 1000 watts, power P = IV, thus for a mains of 250 V, the maximum permissible Current I = \(\frac{\text{P}}{\text{V}}\) = \(\frac{1000}{250}\) = 4 A
Thus, the fuse rating in the plug should be 4 A
Putting safety into consideration, the appropriate rating of the fuse should be 5A
That is = 4 x 1.25 = 5A ( 1.25 = safety factor)
Source: Myschool Past Questions Archive (Record #12033)