A hot plate of an electric oven connected to a 220 V line has two resistance coils

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 resistances, which may be used separately, in series, or in parallel. What are the currents in the three cases?

Solution:

Supply voltage, V = 220 V

Here Resistance of one coil, R =24 Ω

(i) Coils are used separately

According to Ohm’s law, V=I₁R₁

 I₁ is the current flowing through the coil

I₁=V/R₁=220/24=9.166A

∴ current flow through the coil when used separately is 9.16 A.

 (ii) Coils are connected in series

R₂=24 Ω+24 Ω=48 Ω

According to Ohm’s law

I₂=V/R₂=220/48=4.58A

the current flowing through the series circuit is 4.58A

(iii) Coils are connected in parallel

 

According to Ohm’s law

I₃=V/R₃=220/12=18.33A

the current flowing through the parallel circuit is 18.33A