L, C and R represent physical quantities inductance, capacitance and resistance respectively. The combination representing the dimension of frequency will be:

1. LC

2. (LC)^–1/2

3. ${\left(\frac{{\displaystyle L}}{{\displaystyle C}}\right)}^{-1/2}$

4. $\frac{C}{L}$

In an ac circuit, a resistance of R ohm is connected in series with an inductance L. If the phase angle between voltage and current is 45°, the value of inductive reactance will be:

In the circuit shown below, the ac source has voltage $V=20\cos \left(\omega t\right)$ volts with ω = 2000 rad/sec.  The amplitude of the current is closest to:
         

1. 2 A

2. 3.3 A

3. $2/\sqrt{5}\mathrm{ \; A}$

4. $\sqrt{5}\mathrm{ \; A}$

An inductor of inductance L and resistor of resistance R are joined in series and connected by a source of frequency ω. The power dissipated in the circuit is:

1. $\frac{(R^2+{\omega }^2{L}^2)}{V}$

2. $\frac{V^{2}R}{(R^2+{\omega }^2{L}^2)}$

3. $\frac{V}{(R^2+{\omega }^2{L}^2)}$

4. $\frac{\sqrt{R^2+{\omega }^2{L}^2}}{V^2}$

In an LCR circuit, the potential difference between the terminals of the inductance is 60 V, between the terminals of the capacitor is 30 V and that between the terminals of the resistance is 40 V. The supply voltage will be equal to:

1. 50 V

2. 70 V

3. 130 V

4. 10 V

In a circuit, L, C and R are connected in series with an alternating voltage source of frequency f. The current leads the voltage by 45°. The value of C will be:

1. $\frac{1}{2\pi f(2\pi fL+R)}$

2. $\frac{1}{\pi f(2\pi fL+R)}$

3. $\frac{1}{2\pi f(2\pi fL-R)}$

4. $\frac{1}{\pi f(2\pi fL-R)}$

In the circuit shown below, what will be the readings of the voltmeter and ammeter?
           

1. 800 V, 2 A

2. 300 V, 2 A

3. 220 V, 2.2 A

4. 100 V, 2 A

An ac source of angular frequency ω is fed across a resistor r and a capacitor C in series. I is the current in the circuit. If the frequency of the source is changed to ω/3 (but maintaining the same voltage), the current in the circuit is found to be halved. Calculate the ratio of reactance to resistance at the original frequency ω.
1. $\sqrt{\frac{3}{5}}$
2. $\sqrt{\frac{2}{5}}$
3. $\sqrt{\frac{1}{5}}$
4. $\sqrt{\frac{4}{5}}$

For a series RLC circuit, R = X_L = 2X_C. The impedance of the circuit and phase difference between V and i will be:

1. $\frac{\sqrt{5}R}{2},$ ${\tan }^{-1}\left(2\right)$

2. $\frac{\sqrt{5}R}{2},{\tan }^{-1}\left(\frac{{\displaystyle 1}}{{\displaystyle 2}}\right)$

3. $\sqrt{5}{X}_C,{\tan }^{-1}\left(2\right)$

4. $\sqrt{5}R,$ ${\tan }^{-1}\left(\frac{{\displaystyle 1}}{{\displaystyle 2}}\right)$

In a series LCR circuit, which one of the following curves represents the variation of impedance (Z) with frequency (f)?

1.		2.
3.		4.