Q. No.The variation of EMF with time for four types of generators is shown in the figures. Which amongst them can be called AC voltage?
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| (a) | (b) |
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| (c) | (d) |
| 1. | (a) and (d) |
| 2. | (a), (b), (c), and (d) |
| 3. | (a) and (b) |
| 4. | only (a) |
In a heating arrangement, an alternating current having a peak value of \(28~\mathrm{A}\) is used. To produce the same heat energy, if direct current is used to produce the same amount of heat, then its magnitude will be:
| 1. | about \(14~\mathrm{A}\) | 2. | about \(28~\mathrm{A}\) |
| 3. | about \(20~\mathrm{A}\) | 4. | cannot say |
A light bulb is rated at \(100~\text{W}\) for a \(220~\text{V}\) AC supply. The RMS current through the bulb is:
1. \(0.243\) A
2. \(0.454\) A
3. \(0.222\) A
4. \(0.312\) A
1. \(100~\text{mA}\)
2. \(200~\text{mA}\)
3. \(20~\text{mA}\)
4. \(10~\text{mA}\)
| 1. | \(1 / \sqrt{2}\) times the rms value of the ac source. |
| 2. | the value of voltage supplied to the circuit. |
| 3. | the rms value of the ac source. |
| 4. | \(\sqrt{2}\) times the rms value of the ac source. |
1. \(0.707\) A
2. \(1\) A
3. \(1.414\) A
4. \(2\) A
An AC source is rated \(220~\mathrm{V}\), \(50~\mathrm{Hz}\). The average voltage is calculated in a time interval of \(0.01~\mathrm{s}\). It,
| 1. | must be zero |
| 2. | may be zero |
| 3. | is never zero |
| 4. | is \(220\sqrt{2}\) V |
A \(15.0~\mathrm{\mu F}\) capacitor is connected to a \(220~\mathrm{V}\), \(50~\mathrm{Hz}\) source. If the frequency is doubled, what happens to the capacitive reactance and the current?
| 1. | the capacitive reactance is halved and the current is doubled. |
| 2. | the capacitive reactance is doubled and the current is halved. |
| 3. | the capacitive reactance remains the same and the current is doubled. |
| 4. | the current remains the same and the capacitive reactance is halved. |
A resistor of \(200~\mathrm{\Omega}\) and a capacitor of \(15.0~\mathrm{\mu F}\) are connected in series to a \(220~\mathrm{V}\), \(50\) Hz ac source. The voltage (RMS) across the resistor and the capacitor are respectively:
1. \( 160.3 \mathrm{~V}, 160.3 \mathrm{~V} \)
2. \( 151 \mathrm{~V}, 151 \mathrm{~V} \)
3. \( 160.3 \mathrm{~V}, 151 \mathrm{~V} \)
4. \( 151 \mathrm{~V}, 160.3 \mathrm{~V}\)
| 1. | \(60^\circ\) | 2. | \(90^\circ\) |
| 3. | \(30^\circ\) | 4. | \(45^\circ\) |
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