Test: Superposition Theorem - Electrical Engineering (EE) MCQ

 In superposition theorem, whether we consider the effect of a voltage or current source, voltage sources are always shorted and current sources are always opened.

When we consider the 16V source, we short the 10V source and open the 15A and 3A source. From the resulting series circuit we can use voltage divider to find Vx.
Vx= 16*20/(20+80)=3.2A.

Due to the 3A source, we short the 16V and 10V source and open the 15A source. From the resulting circuit, we can use current divider to find the current in the 20 ohm branch and then multiply it with the resistance to find the voltage.
I20= 3*80/(20+80)=2.4A
Vx=20*2.4=48V.

Due to the effect of the 10V source, we short the 16V source and open the 3A and 15A source. From the resulting series circuit, we can use voltage divider to find the value of Vx.
Vx=10*20/(80+20)=2V.

Due to the 15V source, the 10V and 16V sources get shorted and the 3A source acts as an open circuit. Since the 10V source is shorted, it acts as a low resistance path and current flows only within that loop and do not flow to the 20 ohm resistor. Hence the voltage is 0V.

Due to 15 A current source, 10V and 16V sources get shorted and the 3A source acts as an open circuit. Since the 10V source is shorted, it acts as a low resistance path and current flows only within that loop and do not flow to the 20 ohm resistor. Hence the voltage is 0V.

Superposition theorem is valid only for linear systems because the effect of a single source cannot be individually calculated in a non-linear system.

Due to the 3A source, we short the 16V and 10V source and open the 15A source.
From the resulting circuit, we can use current divider to find the current in the 20 ohm branch and then multiply it with the resistance to find the voltage.

I20 = 3*80/(20+80)=2.4A

Vx=20*2.4=48V.

Power across an element is not equal to the power across it due to all the other sources in the system. The power in an element is the product of the total voltage and the total current in that element.

Due to the effect of the 10V source, we short the 16V source and open the 3A and 15A source.
From the resulting series circuit, we can use voltage divider to find the value of Vx.
Vx=10*20/(80+20)=2V.