 Question 13

# A hot plate of an electric oven connected to a 220 V line has two resistance coils A and B, each of 24 Ω resistance, which may be used separately, in series, or in parallel. What are the currents in the three cases?

Supply voltage, V = 220 V

Resistance of one coil, R = 24 Ω

(i) Coils are used separately

According to Ohm’s law,

V = I1R1

Where,

Iis the current flowing through the coil Therefore, 9.16 A current will flow through the coil when used separately.

(ii) Coils are connected in series

Total resistance, R2 = 24 Ω + 24 Ω = 48 Ω

According to Ohm’s law,

V = I2R2

Where,

I2 is the current flowing through the series circuit Therefore, 4.58 A current will flow through the circuit when the coils are connected in series.

(iii) Coils are connected in parallel

Total resistance, R3 is given as According to Ohm’s law,

V = I3R3

Where,

Iis the current flowing through the circuit Therefore, 18.33 A current will flow through the circuit when coils are connected in parallel.