 # A hot plate of an electric oven connected to a 220 V line has two resistance coils A and B, each of 24 resistances, 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= 24Ω

(i) Coils are used separately

According to Ohm’s law, V= I1R1

Where I1 is the current flowing through the coil

I1 = V/R1 = 220/24 = 9.166 A,

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

I2 = V/R2 = 220/48 = 4.58 A,

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 I3 is the current flowing through the circuit

I3 = V/R3 = 220/12 = 18.33 A,

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