RLC Circuit

Q. The reading of ammeter in the circuit shown will be

1. 2A
2. 2.4 A
3. Zero
4. 1.7 A

Q. What is the proof for propagation of errors in parallel combination of resistors

Q. Find the potential difference between $(0,-2,3)$ and $(1,3,4)$ for the electric field $\overrightarrow{E}=5\hat{i}-\hat{k}$ in space.

1. $-4\text{V}$
2. $-6\text{V}$
3. $12\text{V}$
4. $-8\text{V}$

Q. Unit of electric flux is

1. $\frac{\text{N}}{{\text{m}}^2-\text{C}}$
2. ${\text{N-m}}^2\text{/C}$
3. $\frac{\text{N}}{{\text{C}}^2-{\text{m}}^2}$
4. $\text{N-m}\text{/C}$

Q. Find the potential at node A.

1. $-\frac{5}{3}\text{V}$
2. $+\frac{5}{3}\text{V}$
3. $+\frac{4}{3}\text{V}$
4. $-\frac{2}{3}\text{V}$

Q. Refer to the circuit diagram and the corresponding graphs. The current rises when key $K$ is pressed. With $R=R_1$ and $L=L_1$ the rise of current is shown by curve (1), while curve (2) shows the rise of current when $R=R_2$ and $L=L_2$. The maximum current is same for both curves, then :

1. $R_1=R_2,L_1=L_2$
2. $R_1>R_2,L_1=L_2$
3. $R_1>R_2,L_1<L_2$
4. $R_1=R_2,L_1<L_2$

Q. A coil has resistance $30\Omega$ and inductive reactance $200\Omega$ at $50\text{Hz}$ frequency. If an AC supply of $200\text{V},100\text{Hz}$ is connected across the coil, the current in the coil will be

1. $6\text{A}$
2. $10\text{A}$
3. $4\text{A}$
4. $8\text{A}$

Q. Select correct alternative(s)
If both plates of parallel plate capacitor are given positive charge as shown in figure and at $t=0$ switch is closed:

1. Current in resistance 'R' will flow from A to B
2. Current in resistance 'R' will flow from B to A
3. Current in the circuit at t is $\frac{Q}{2RC}{e}^{-t/RC}$
4. Total heat developed in the circuit long after switch is closed is $\frac{Q^2}{4C}$

Q. The length of a sonometer wire AB is 110 cm.Where should the two bridges be placed from A to divide the wire in 3 segments whose fundamental frequencies are in the ratio 1:2:3 ?

Q. Find the potential at node A.

1. $+\frac{5}{3}\text{V}$
2. $+\frac{4}{3}\text{V}$
3. $-\frac{2}{3}\text{V}$
4. $-\frac{5}{3}\text{V}$

Q.

In the circuit shown in the figure, reading of voltmeter is $V_1$ when only $S_1$ is closed, $V_2$ when only $S_2$ is closed and $V_3$ when both $S_1$ and $S_2$ are closed. Choose the correct relation between $V_1$, $V_2$ and $V_3$.

1. $V_2>V_1>V_3$

2. $V_3>V_2>V_1$

3. $V_3>V_1>V_2$

4. $V_1>V_2>V_3$

Q. A voltage of peak value $283\text{V}$ and varying frequency is applied to a series $L-C-R$ combination in which $R=3\Omega ;L=25\text{mH}$ and $C=400\mu F$. Then, the frequency (in $Hz$) of the source at which maximum power is dissipated in the above, is

1. $51.6$
2. $50.7$
3. $51.1$
4. $50.3$

Q. In the circuit shown $k_1$ is closed for a long time. Then $k_1$ is opened and $k_2$ is closed simultaneously. If $R=20\Omega ,L=30mH$ and $C=12\mu F$, then maximum charge on the capacitor will be

1. $3\times {10}^{-3}C$
2. $5\times {10}^{-3}C$
3. $10\times {10}^{-3}C$
4. $12\times {10}^{-3}C$

Q. Refer to the circuit diagram and the corresponding graphs. The current rises when key $K$ is pressed. With $R=R_1$ and $L=L_1$ the rise of current is shown by curve (1), while curve (2) shows the rise of current when $R=R_2$ and $L=L_2$. The maximum current is same for both curves, then :

1. $R_1=R_2,L_1=L_2$
2. $R_1>R_2,L_1=L_2$
3. $R_1>R_2,L_1<L_2$
4. $R_1=R_2,L_1<L_2$

Q. When an inductor, a capacitor and a resistor are connected in series across a source of alterating emf, the potential difference across the inductor, capacitor and resistor are 70V, 30V and 30V respectively. Find the emf of the source

1. 50V
2. 60V
3. 30V
4. 80V

Q. A telephone wire of length 200 km has a capacitance of 0.014$\mu$F per km. If it carries an ac of frequency 2.5 kHz, what should be the value of an inductor required to be connected in series so that the impedance of the circuit is minimum

1. 0.35 mH
2. 35 mH
3. 1.4 mH
4. Zero

Q. An inductive coil has a resistance of $100\Omega$. When an A.C. signal of frequency $1000\text{Hz}$ is fed to the coil, the applied voltage leads the current by ${45}^{\circ }$. What is the approximate inductance of the coil (in $\text{mH}$) ?

Q. A telephone wire of length 200 km has a capacitance of 0.014$\mu$F per km. If it carries an ac of frequency 2.5 kHz, what should be the value of an inductor required to be connected in series so that the impedance of the circuit is minimum

1. 0.35 mH
2. 35 mH
3. 1.4 mH
4. Zero

Q. A series LCR circuit containing a resistor of $120\Omega$ has an angular resonant frequency $4\times {10}^{5}rad{s}^{-1}$. At resonance the voltages across resistor and inductor are 60 V and $40\text{V}$ respectively.
The value of capacitance C is

1. $\frac{1}{32}\mu F$
2. $\frac{1}{16}\mu F$
3. $32\mu F$
4. $16\mu F$

Q. In the circuit shown in figure neglecting source resistance, the voltmeter and ammeter readings will respectively be

1. $0\text{V},3\text{A}$
2. $150\text{V},3\text{A}$
3. $150\text{V},6\text{A}$
4. $0\text{V},8\text{A}$

Q. The inductance of a solenoid is $5\text{H}$ and its resistance is $5\Omega$. If it is connected to a $10\text{Volt}$ battery, then time taken by the current to reach ${\frac{9}{10}}^{th}$ of its maximum will be

1. $4.0\text{s}$
2. $2.3\text{s}$
3. $1.4\text{s}$
4. $1.2\text{s}$

Q. In an LCR circuit ohm. When capacitance C is removed, the current lags behind the voltage by $\frac{\pi }{3}$ . When inductance L is removed, the current leads the voltage by $\pi$. The impedance of the circuit is

1. 50 ohm
2. 100 ohm
3. 200 ohm
4. 400 ohm

Q. An inductor of inductance $L=5\text{H}$ is connected to an $\text{AC}$ source having voltage $E=10\sin (10t+\frac{\pi }{6})$. Find the maximum value of current in the circuit.

Q. What will be the self inductance of a coil, to be connected in a series with a resistance of $\pi \sqrt{3}\Omega$ such that the phase difference between the emf and the current at 50 Hz frequency is ${30}^{\circ }$

1. 0.5 Henry
2. 0.03 Henry
3. 0.05 Henry
4. 0.01 Henry

Q. Unit of electric flux is

Q. Given below is the curve between maximum value of current $\left(i_m\right)$ and angular frequency $\left(\omega \right)$ for three different series LCR circuits at same voltage. For which curve, the value of resistance of the resistor is maximum?

1. Curve - $3$
2. All the curve have equal value of resistance of the resistor.
3. Curve - $1$
4. Curve - $2$

Q. In the figure shown, the charge on the capacitor is $q=\left(4t^2\right)\text{C}$ then $V_{ab}$ at $t=1\text{s}$ is

1. $30\text{V}$
2. $-30\text{V}$
3. $20\text{V}$
4. $-20\text{V}$

Q. What will be the self inductance of a coil, to be connected in a series with a resistance of $\pi \sqrt{3}\Omega$ such that the phase difference between the emf and the current at 50 Hz frequency is ${30}^{\circ }$

1. 0.5 Henry
2. 0.03 Henry
3. 0.05 Henry
4. 0.01 Henry

Q. The $\text{RMS}$ value of potential difference $V$ shown in the figure is

1. $V_0$
2. $\frac{V_0}{2}$
3. $\frac{V_0}{\sqrt{3}}$
4. $\frac{V_0}{\sqrt{2}}$