The r.m.s. value of the potential difference V shown in the figure is:
1.
2.
3.
4.
A coil has a resistance of \(30~ \mathrm{ohm}\) and inductive reactance of \(20 ~\mathrm{ohm}\) at a \(50~\mathrm{ Hz}\) frequency. If an \(\mathrm{ac}\) source of \(200 ~\mathrm{volts,}\) \(100~\mathrm{ Hz}\) is connected across the coil, the current in the coil will be:
1. | \(2.0~\mathrm{ A}\) | 2. | \(4.0~\mathrm{ A}\) |
3. | \(8.0~\mathrm{ A}\) | 4. | \(20/\sqrt{13}~\mathrm{A}\) |
The instantaneous values of alternating current and voltages in a circuit are given as,
\(i=\frac{1}{\sqrt{2}}\sin\left ( 100\pi t \right )~\text{Ampere}\)
\(e=\frac{1}{\sqrt{2}}\sin\left ( 100\pi t+\pi /3 \right )~\text{Volt}\)
What is the average power consumed by the circuit in watts?
1. | \( \frac{\sqrt{3}}{4} \) | 2. | \( \frac{1}{2} \) |
3. | \( \frac{1}{8} \) | 4. | \( \frac{1}{4}\) |
Turn ratio of a step-up transformer is \(1: 25\). If current in load coil is \(2~\text{A}\), then the current in primary coil will be:
1. | \(25~\text{A}\) | 2. | \(50~\text{A}\) |
3. | \(0.25~\text{A}\) | 4. | \(0.5~\text{A}\) |
A lamp is connected in series with a capacitor. AC and DC sources are connected to the circuit one by one, then mark the correct statement/s.
1. | when the DC source is connected to the capacitor, the lamp will not glow in a steady-state condition. |
2. | when the AC source is connected to the capacitor and the capacitance of the capacitor is reduced, the lamp will glow less brightly. |
3. | when the DC source is connected to the capacitor and the capacitance of the capacitor is reduced, the lamp will glow less brightly. |
4. | both (1) and (2). |
A series LCR circuit containing \(5.0~\text{H}\) inductor, \(80~\mu \text{F}\) capacitor and \(40~\Omega\) resistor is connected to \(230~\text{V}\) variable frequency AC source. The angular frequencies of the source at which power transferred to the circuit is half the power at the resonant angular frequency are likely to be:
1. | \(46~\text{rad/s}~\text{and}~54~\text{rad/s}\) |
2. | \(42~\text{rad/s}~\text{and}~58~\text{rad/s}\) |
3. | \(25~\text{rad/s}~\text{and}~75~\text{rad/s}\) |
4. | \(50~\text{rad/s}~\text{and}~25~\text{rad/s}\) |
When does the voltage in a series LCR circuit lead the current? (Given that resonant angular frequency)
1.
2.
3.
4. None of these
In a series LC circuit, if and is connected to a 100 V-50 Hz a.c. source, the impedance of the circuit is:
1.
2.
3.
4. None of these
In a series LCR circuit, the phase difference between voltage across L and voltage across C is equal to:
1. | Zero | 2. | \(\pi\) |
3. | \(\pi \over 2\) | 4. | \(2\pi\) |
In a series RLC circuit, potential differences across R, L and C are 30 V, 60 V and 100 V respectively, as shown in the figure. The emf of the source (in volts) will be:
1. 190
2. 70
3. 50
4. 40