Q. 95.0( 4 Votes )

For a heater rated at 4 kW and 220 V, calculate:(a) the current,(b) the resistance of the heater,(c) the energy consumed in 2 hours, and(d) the cost if 1 kWh is priced at ₹ 4.60

(a) Here, P = 4kw, V = 220v

I = ?

We know that

Power = VI = 220 × I

4000 = 220I

I = 4000/220= 18.18A

(b) Here, P = 4kw, V = 220v

R = ?

We know that,

P = I2R

P = (18.18)2×R

R = 4000/(18.18)2

R = 12.10 Ω

(c) Here, P = 4kw, time = 2hr

Energy consumed in two hour = P × t

= 4 × 2

= 8kw-hr

(d) If 1kwh = Rs 4.6

Here, Energy consumed in two hour = 8kwh

So, total cost = 8 x 4.6 = Rs 36.8

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