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

Answer :

(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 = I^{2}R

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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