Question

An electric iron rated 1100 W, 220 V is operated for 5 hours.

Calculate:

1. the minimum rating of the fuse required.
2. the energy consumed in kWh.
3. the cost of the energy consumed, if the rate is ₹ 10 per unit.

Answer 1

Given: Power rating of the iron (P) = 1100 W

Voltage rating of the iron (V) = 220 V

Operating time = 5 hours

a. Power consumed by an appliance is given by,

P = VI

⇒ I = `P/V`

= `1100/220`

= 5 A

Here, I is the operating current flowing through the appliance.

Since the fuse rating should be slightly higher than the operating current, the minimum suitable fuse rating is 6 A.

Hence, 6 A is the minimum rating of the fuse required.

b. Energy consumed by the iron = Power consumed × Operating time

= 1100 × 5

= 5500 Wh

= 5.5 × 10³ Wh

= 5.5 kWh

Hence, the energy consumed by the iron is 5.5 kWh.

c. Given: Electricity rate = ₹ 10 per unit

As, 1 unit = 1 kWh

Then,

The cost of energy consumed by the iron = Energy consumed × Electricity rate

= 5.5 × 10

= ₹ 55

Hence, the cost of the energy consumed is ₹ 55.