This question was previously asked in

IPRC (ISRO) Technician B (Electronics) 2018 Official Paper (Held on 22 April 2018)

Option 2 : 5 V

__Concept__:

RLC series circuit:

The resultant voltage is given as;

\(V = \sqrt {V_1^2 + {{\left( {{V_2} - {V_3}} \right)}^2}} \)

Where,

V1 = voltage across the resistor

V2 = voltage across the inductor

V3 = voltage across the capacitor

V = resultant voltage

In the case of RL (V_{3} = 0) circuit resultant voltage is given as;

\(V = \sqrt {(V_1)^2 + {{\left( {{V_2}} \right)}^2}} \) -----(1)

__Calculation:__

Given

V1 = 3 V, V2 = 4 V,

So, from equation (1);

\(V = \sqrt {(3)^2 + {{\left( {{4}} \right)}^2}} \)

V = 5 V

**The source voltage is 5 V**

__Additional Information__

For a series RLC circuit, the net impedance is given by:

Z = R + j (XL - XC)

XL = Inductive Reactance given by:

XL = ωL

XC = Capacitive Reactance given by:

XL = 1/ωC

ω = 2 π f

ω = angular frequency

f = linear frequency

The magnitude of the impedance is given by:

\(|Z|=\sqrt{R^2+(X_L-X_C)^2}\)