An electric iron rated 1100 W, 220 V is operated for 5 hours.
Calculate:
(a) the minimum rating of the fuse required.
(b) the energy consumed in kWh.
(c) the cost of the energy consumed, if the rate is ₹ 10 per unit.
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Given,
- Power rating of the iron ($\text P$) = 1100 W
- Voltage rating of the iron ($\text V$) = 220 V
- Operating time = 5 hours
(a) Power consumed by an appliance is given by,
$$\begin{aligned}\text P = \text {VI} \\[1em] \Rightarrow \text I = \frac{\text P}{\text V} \\[1em] = \frac{1100}{220} \\[1em] = 5\ \text A\end{aligned}$$
Here, $\text I$ is the operating current flowing through the appliance.
Since the fuse rating should be slightly higher than the operating current, so 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 x Operating time
= 1100 x 5
= 5500 Wh
= 5.5 x 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 x Electricity rate
= 5.5 x 10
= ₹ 55
Hence, the cost of the energy consumed is ₹ 55.