Question

In an L-C-R series circuit, the potential difference between the terminals of the inductance is 60 V, between the terminals of the capacitor is 30 V and that across the resistance is 40 V. Then, the supply voltage will be equal to
A. 10 V
B. 50 V
C. 70 V
D. 130 V

Answer 1

Correct Answer - B
Given, `V_(L)`=60 V, `V_(C) = 30V, V_(R) = 40 V`
According to L-C-R series circuit, we know that

In phasor diagram, `V_(C)` and `V_(L)` are in anti-phase to each other due to their `90^(@)` leading and lagging relationship with the circuit current `I_(S)`.

So, `V_(S) = sqrt((V_(L)-V_(C))^(2)+V_(R)^(2)) = sqrt((60-30)^(2)+(40)^(2))`
`=sqrt((30)^(2)+(40)^(2)) = sqrt(900 + 1600)= sqrt(2500) = 50 V`