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 = 250 × I


4000 = 250I


I = 16amp


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


R = ?


We know that,


P = I2R


P = 162×R


R = 4000/162


R = 15.25 ohm


(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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