Question

In norma use, a current of 3.5 A flows through a hair dryer. Choose a suitable fuse from the following
(a) 3 A
(b) 5 A
(c) 10 A
(d) 30 A

Answer 1

The 5A fuse is suitable for the safety of hair dryer.

Explanation:

Given: In normal use, a current of 3.5 A flows through a hair dryer.

The safety factor is range from 1.2~1.5.

The safe current for hair dryer is given by

$= > \: 3.5 \times 1.2$

$= > \: 4.2 \: ampere$

So, for 4.2 A the 5A fuse is suitable for the safety of hair dryer.

Answer 2

Answer is option (b)

Explanation:

• A hairdryer can handle a current of 5 A when used normally.

• The fuse required should be of 5A.

Neither, A 3 amp fuse is insufficient and will eventually blow with a current of 4 amps whereas 13 Amp fuse will be very high. Fuses should be 5 or 6 amp device.

Further, the Safety factor, is taken to be 1.2, hence safe current will be

I = $1.2 \times 3.5$

= 4.3 or 5 Amp