Question

An A.C. voltmeter reads 20 V across a resistor, 30 V across an inductor and 15 V across a capacitor in LCR series circuit. In this case the supply voltage will be

• A. 100 V
• B. 60 V
• C. 50 V
• D. 25 V

Answer 1

Answer: (D)

25 V

Answer 2

V_R = 20 V

V_L = 30 V

V_C = 15 V

V_supply = $\sqrt{(V_{L}–V_{C})^{2} + V_{R}^{2}}$

= $\sqrt{(30–15)^{2} + 20^{2}}$ = $\sqrt{225 + 400}$ = 25 volt