The variation of EMF with time for four types of generators is shown in the figures. Which amongst them can be called AC voltage?

   
(a) (b)
   
(c) (d)

Choose the correct option from the given ones:

1. (a) and (d)
2. (a), (b), (c), and (d)
3. (a) and (b)
4.  only (a)

Subtopic:  AC vs DC |
 79%
Level 2: 60%+
NEET - 2019
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In a heating arrangement, an alternating current having a peak value of \(28~\text{A}\) 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 \(14~\text{A}\)  2. about \(28~\text{A}\)
3. about \(20~\text{A}\) 4. cannot say
Subtopic:  AC vs DC |
 57%
Level 3: 35%-60%
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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. \( \frac{1}{4}\)
Subtopic:  Power factor |
 76%
Level 2: 60%+
AIPMT - 2012
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For a series \(\mathrm{LCR}\) circuit, the power loss at resonance is:
1. \(\frac{V^2}{\left[\omega L-\frac{1}{\omega C}\right]}\)

2. \( \mathrm{I}^2 \mathrm{~L} \omega \)

3. \(I^2 R\)

4. \( \frac{\mathrm{V}^2}{\mathrm{C} \omega} \)

Subtopic:  Power factor |
 81%
Level 1: 80%+
AIPMT - 2002
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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

Subtopic:  RMS & Average Values |
 80%
Level 1: 80%+
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A \(15.0~{\mu \text F}\) capacitor is connected to a \(220~\text {V},\) \(50~\text {Hz}\) 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.

Subtopic:  Different Types of AC Circuits |
 81%
Level 1: 80%+
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A resistor of \(200~\mathrm{\Omega}\) and a capacitor of \(15.0~\mu\text{F}\) are connected in series to a \(220~\text{V}\), \(50\) Hz AC source. The voltage (RMS) across the resistor and the capacitor are respectively:
1. \( 160.3 ~\text{V}, 160.3 ~\text{V} \)
2. \( 151 ~\text{V}, 151 ~\text{V} \)
3. \( 160.3 ~\text{V}, 151 ~\text{V} \)
4. \( 151 ~\text{V}, 160.3 ~\text{V}\)

Subtopic:  Different Types of AC Circuits |
Level 3: 35%-60%
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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

Subtopic:  RMS & Average Values |
 52%
Level 3: 35%-60%
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An AC source rated \(100~\text{V}\) (rms) supplies a current of \(10~\text{A}\) (rms) to a circuit. The average power delivered by the source:

(a) must be \(1000~\text{W}\).
(b) may be \(1000~\text{W}\).
(c) may be greater than \(1000~\text{W}\).
(d) may be less than \(1000~\text{W}\).
Choose the correct option:
1. (a) only
2. (b), (c)
3. (b), (d)
4. (a), (d)

Subtopic:  Power factor |
 65%
Level 2: 60%+
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A transformer is used to light a \(100~\text{W}\) and \(110~\text{V}\) lamp from a \(220~\text{V}\) main. If the main current is \(0.5~\text{A},\) the efficiency of the transformer is approximately:
1. \(30\%\)
2. \(50\%\)
3. \(90\%\)
4. \(10\%\)

Subtopic:  Transformer |
 74%
Level 2: 60%+
AIPMT - 2007
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