What is the average power dissipated in the ac circuit if current i = 100sin100t A and V=100sin(100t+π/3) volts?
1. 2500 W
2. 250 W
3. 5000 W
4. 4000 W
A bulb is rated at 100 V, 100 W, and is treated as a resistor. The inductance of an inductor (choke coil) that should be connected in series with the bulb to operate the bulb at its rated power with the help of an ac source of 200 V and 50 Hz is:
1. \(\frac{\pi }{\sqrt{3}}~H\)
2. \(100~H\)
3. \(\frac{\sqrt{2}}{\pi }~H\)
4. \(\frac{\sqrt{3}}{\pi }~H\)
When an alternating voltage is given as \(E = (6 sin\omega t - 2 cos \omega t)\) volt, what is its RMS value?
1. \(4 \sqrt 2 \) V
2. \(2 \sqrt 5\) V
3. \(2 \sqrt 3\) V
4. \(4\) V
The circuit is in a steady state when the key is at position 1. If the switch is changed from position 1 to position 2, then the steady current in the circuit will be:
1. \(E_o \over R\)
2. \(E_o \over 3R\)
3. \(E_o \over 2R\)
4. \(E_o \over 4R\)
In a box Z of unknown elements (L or R or any other combination), an ac voltage is applied and the current in the circuit is found to be . The unknown elements in the box could be:
1. | Only the capacitor |
2. | Inductor and resistor both |
3. | Either capacitor, resistor, and an inductor or only capacitor and resistor |
4. | Only the resistor |
A capacitor of capacitance 1 is charged to a potential of 1 V. It is connected in parallel to an inductor of inductance H. What is the value of the maximum current that will flow in the circuit?
In a series LCR circuit, the current through the ac source is 2 A. If resistor R has a resistance of 10 Ω, the average power dissipated in the circuit is:
1. 20 W
2. 30 W
3. 10 W
4. 40 W
It is found that the current through the LCR series circuit is at its maximum. If are potential differences across resistance, capacitor, and inductor respectively, then which of the following is correct?
1. | \(V_r=V_L>V_C\) |
2. | \(V_R \neq V_L=V_C\) |
3. | \(V_R \neq V_L \neq V_C\) |
4. | \(V_R=V_C \neq V_L\) |
An alternating voltage (in volts) given by \(V=200\sqrt{2}sin100t\) is connected to a\(1~\mu F\) capacitor through an \(ac\) ammeter. The reading of the ammeter will be:
1. | \(10~ \mathrm{mA}\) | 2. | \(20~ \mathrm{mA}\) |
3. | \(40~ \mathrm{mA}\) | 4. | \(80~ \mathrm{mA}\) |
Voltage and current in an ac circuit are given by \(V=5sin\left ( 100\pi t-\frac{\pi }{6}~ \right )~V\) and \(I=4sin\left ( 100\pi t+\frac{\pi }{6}~ \right )~A.\)
Hence:
1. | The voltage leads the current by 30°. |
2. | The current leads the voltage by 30°. |
3. | The current leads the voltage by 60°. |
4. | The voltage leads the current by 60°. |