Question

current passing through 1ohm resistance is zero in the circuit show below then find emf E is

Answer 1

The emf E  in the circuit is 6 volts.

Explanation:

Using superposition theorem ,

when 6v source is considered and E is short circuited

Total resistance = 2 II 1 = 2/3 Ω

Hence current,

I = V/R = 6/2/3 = 9 A

Hence current in the 1Ω resistance due to 6v source

I₁ = 9 x 2/(2+1) = 6A

Similarly when E source is acting and 6v source is short circuited,

Then There will be no current flowing in the 2 Ω resistance as it will be short circuited.

Hence current in the 1Ω resistance

I₂ = V/R = E/1 = E amp

Since net current in the 1Ω resistor is 0, hence

I₁ - I₂ = 0

=> 6 - E = 0

=> E = 6v

Hence the emf E is 6 volts.