Question

a circuit has a fuse of 5a.find the maximum number of 100w 220v bulbs that can be used in a circuit.

Answer 1

Answer:

Explanation:

Given :-

Power, P = 100 W

Voltage, V = 220 V

Now current, I  max = 5 A

To Find :-

Number of bulbs which can be used, n = ???

Formula to be used :-

From Relation, P = VI

We Have, I = P/V

Solution :-

Putting all the values, we get

⇒ I = 100/220

⇒ A = 5/11 A

For bulb, in parallel, I max = n I

We have, n = I max/ I

Putting values, we get

⇒ n = 5 × 11/5

⇒ n = 11

Hence, 11 bulbs can be used safely in the circuit.

Answer 2

Explanation:

Since fuse is of 5A, current won't exceed 5A.

P=IV

100=I×220V

I=0.45A(approx)

Thus current through 1 bulb is 0.45.

So no.of bulbs connected 0.45×n which should be less than 5A.

Hence, n=11 bulbs which should be connected in parallel.