Q. No.If the RMS current in a \(50~\text{Hz}\) AC circuit is \(5~\text{A}\), the value of the current \(\dfrac{1}{300}~\text{s}\) after its value becomes zero is:
| 1. | \(5\sqrt2~\text{A}\) | 2. | \(5\sqrt{\dfrac32}~\text{A}\) |
| 3. | \(\sqrt{\dfrac56}~\text{A}\) | 4. | \(\dfrac{5}{\sqrt2}~\text{A}\) |
An alternating current generator has an internal resistance \(R_{g}\) and an internal reactance \(X_{g}\). It is used to supply power to a passive load consisting of a resistance \(R_{g}\) and a reactance \(X_{L}\). For maximum power to be delivered from the generator to the load, the value of \(X_{L}\) is equal to:
1. zero
2. \(X_g\)
3. \(-X_g\)
4. \(R_g\)
| 1. | input voltage cannot be AC voltage, but a DC voltage |
| 2. | maximum input voltage is \(220~\text{V}\) |
| 3. | the meter reads not v but \(<v^2>\) and is calibrated to read \(\sqrt{<v^2>}\) |
| 4. | the pointer of the meter is stuck by some mechanical defect |
Which of the following combinations should be selected for better tuning of an LCR circuit used for communication?
1. \(R = 20~\Omega,~L= 1.5~\text{H}, ~C = 35~\mu \text{F}\)
2. \(R = 25~\Omega,~L= 2.5~\text{H}, ~C = 45~\mu \text{F}\)
3. \(R = 15~\Omega,~L= 3.5~\text{H}, ~C = 30~\mu \text{F}\)
4. \(R = 25~\Omega,~L= 1.5~\text{H}, ~C = 45~\mu \text{F}\)
An inductor of reactance \(1~\Omega\) and a resistor of \(2~\Omega\) are connected in series to the terminals of a \(6~\text{V}\) (RMS) AC source. The power dissipated in the circuit is:
1. \(8~\text{W}\)
2. \(12~\text{W}\)
3. \(14.4~\text{W}\)
4. \(18~\text{W}\)
The output of a step-down transformer is measured to be \(24\) V when connected to a \(12\) W light bulb. The value of the peak current is:
| 1. | \(\dfrac{1}{\sqrt{2}}~\text{A}\) | 2. | \(\sqrt{2}~\text{A}\) |
| 3. | \(2~\text{A}\) | 4. | \(2\sqrt{2}~\text{A}\) |
| (a) | Inductor and capacitor |
| (b) | Resistor and inductor |
| (c) | Resistor and capacitor |
| (d) | Resistor, inductor, and capacitor |
1. (b), (c)
2. (c), (d)
3. (b), (d)
4. (a), (d)
| (a) | Only resistor |
| (b) | Resistor and an inductor |
| (c) | Resistor and a capacitor |
| (d) | Only a capacitor |
Choose the correct options:
| 1. | (b), (c) | 2. | (a), (d) |
| 3. | (b), (d) | 4. | (c), (d) |
| (a) | For a given power level, there is a lower current. |
| (b) | Lower current implies less power loss. |
| (c) | Transmission lines can be made thinner. |
| (d) | It is easy to reduce the voltage at the receiving end using step-down transformers. |
| 1. | (a), (b), (c) | 2. | (a), (b), (d) |
| 3. | (b), (c), (d) | 4. | (c), (d) |
| (a) | Here, the power factor \(\cos\phi \ge0, ~P \ge0.\) |
| (b) | The driving force can give no energy to the oscillator \((P=0)\) in some cases. |
| (c) | The driving force cannot syphon out \((P<0)\) the energy out of the oscillator. |
| (d) | The driving force can take away energy out of the oscillator. |
Choose the correct options:
1. (a), (b), (c)
2. (a), (c), (d)
3. (b), (c), (d)
4. (c), (d)
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