Reactance

Q. An AC source rated $220\text{V}$, $50\text{Hz}$ is connected to a resistor. The time taken by the current to change from its maximum to the rms value is:

1. $0.25\text{ms}$
2. $25\text{ms}$
3. $2.5\text{ms}$
4. $2.5\text{s}$

Q. For an AC circuit, calculate the average value of the current per cycle, for which time function of the current is shown in the figure.

1. $\frac{I_0}{2}$
2. $\frac{I_0}{\sqrt{2}}$
3. $\frac{2I_0}{3}$
4. $\frac{3I_0}{4}$

Q. The instantaneous value of emf and current in an A.C. circuit are: $E=1.414sin(100\pi t-\frac{\pi }{4})$, $I=0.707sin\left(100\pi t\right)$ .The reactance of the circuit
will be

1. $\sqrt{2}$ $\frac{1}{2}\Omega$
2. 2$\Omega$
3. $\frac{1}{2}\Omega$
4. $\frac{1}{\sqrt{2}}\Omega$

Q. The instantaneous values of current and voltage in an ac circuit are $I=100sin\left(314\right)t$ A and $E=200sin(314t+\frac{\pi }{3})V$ respectively. If the resistance is 1W then the reactance of the circuit will be

1. $-200\sqrt{3}\Omega$
2. $\sqrt{3}\Omega$
3. $\frac{-200}{\sqrt{3}\Omega }$
4. $100\sqrt{3}\Omega$

Q. A series $\text{LCR}$ circuit connected across $(200\text{V},60\text{Hz})$ source. It consists of a capacitor of capacitive reactance $30\Omega$, a non-inductive resistor of $40\Omega$ and an ideal inductor of inductive reactance $90\Omega$ as shown in the figure. The average power dissipated across the inductor is -



​​​​​​​$[$0.77 Mark$]$

1. $160\text{W}$
2. $50\text{W}$
3. $240\text{W}$
4. Zero

Q. The instantaneous values of current and voltage in an ac circuit are $I=100sin\left(314\right)t$ A and $E=200sin(314t+\frac{\pi }{3})V$ respectively. If the resistance is 1W then the reactance of the circuit will be

1. $-200\sqrt{3}\Omega$
2. $\sqrt{3}\Omega$
3. $\frac{-200}{\sqrt{3}\Omega }$
4. $100\sqrt{3}\Omega$

Q. In the circuit shown in the figure, the ac source gives a voltage $V=20\cos \left(2000t\right)$. Neglecting source resistance, the voltmeter and ammeter readings will be

1. $0\text{V},0.47\text{A}$
2. $1.68\text{V},0.47\text{A}$
3. $0\text{V},1.4\text{A}$
4. $5.6\text{V},1.4\text{A}$

Q. The instantaneous values of current and voltage in an ac circuit are $I=100sin\left(314\right)t$ A and $E=200sin(314t+\frac{\pi }{3})V$ respectively. If the resistance is 1W then the reactance of the circuit will be

1. $-200\sqrt{3}\Omega$
2. $\sqrt{3}\Omega$
3. $\frac{-200}{\sqrt{3}\Omega }$
4. $100\sqrt{3}\Omega$