Question

164 Alternating Current
12. The reading of the A.C. voltmeter in the network
shown in figure is (where V is in volt)
[NCERT Pg. 245]
v
11 Ω
2
Xc = 20 2 x1 = 20 2
11 2
V = 220/2 sinot
(2) 220 V
(4) Zero
(1) 400 V
(3) 200 V
has to

Answer 1

option (3) is correct i.e. 200V

Answer 2

We have to find the reading of alternative current voltmeter in the network shown in figure.

Solution : here V = 220√2 sinωt

So, peak value of voltage = 220√2 volts.

so, RMS value of voltage = Vp/√2 = 220√2/2 = 220 volts.

Now, Z = √{R² + (XL - XC)²}

Here, R = 11 + 11 = 22Ω

XL = XC = 20 Ω

so, R = 22Ω

Now, i = Vrms/Z = 220/22 = 10 A

So voltage across voltmeter = i × XC

= 10 × 20 = 200 Volts.

Therefore the voltage across the voltmeter is 200 volts.