JAMB - Physics (1999 - No. 26)
A 3000W electric cooker is to be used on a 200V mains circuit. Which of the fuses below can be used safely with the cooker?
2A
5A
10A
20A
Giải thích
The maximum current drawn by the cooker is given by;
I = \(\frac{P}{V}\)
∴ I = \(\frac{\text{3000}}{200}\)
I = 15A
The fuse rating = I \(\times\) 125% (the fuse is rated at 125% of the normal operating current)
Hence, the fuse rating = 15A \(\times\) (\(\frac{125}{100}\)) = 18.75amps
Therefore, the best fuse is 20A.