Question

[BT4, CO2] In ac circuit, resistance 5 ohm is connected with capacitor having capacitive reactance 12 ohm. Supply of 260 Vis
connected to the dircuit. Calculate the voltage across resistance.
Select one:
300 V
200 V
240 V
100 V
​

Answer 1

Given:

A circuit is having a 5Ω resistance and a capacitor with 12Ω capacitive reactance in series with a 260V source.

To Find:

The voltage across the resistance.

Solution:

We know that the total impedance of an RC series ac circuit is given by

$Z=\sqrt{R^2+X_C^2}$

where $R$ is the resistance of the circuit and $X_C$ is the capacitive reactance of the circuit

So impedance of this circuit will be $Z=\sqrt{5^2+12^2}$

                                                              $=13$Ω

Using Ohm's law, the current through the circuit, $I=\frac{V}{Z}$

                                                                              $=\frac{260}{13}=20A$

Now voltage across the resistor, $V_R=IR=20*5$

                                                            $=100V$

Hence, the voltage across the resistor is equal to 100V.