An inductor of \(20~\text{mH},\) a capacitor of \(50~ \mu \text{F},\) and a resistor of \(40~ \Omega\) are connected in series across a source of emf \(V= 10\sin340t\). What will be the power loss in the AC circuit?
1. \(0.67~\text{W}\) 2. \(0.78~\text{W}\)
3. \(0.89~\text{W}\) 4. \(0.46~\text{W}\)

Subtopic:  Power factor |
From NCERT
NEET - 2016
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A step–down transformer transforms a supply line voltage of \(2200\) volt into \(220\) volt. The primary coil has \(5000\) turns. The efficiency and power transmitted by the transformer are \(90\%\) and \(8\) kilowatts respectively. How many turns are there in the secondary one?
1. \(5000\)      2. \(50\)       
3. \(500\)         4. \(5\)
Subtopic:  Transformer |
 81%
From NCERT
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Match List I (expression for current) with List II (rms value of current) and select the correct answer.

List I List II
(a) \(I=I_0 \sin \omega t \cos \omega t\) (i) \(I_0\)
(b) \(I=I_0 \sin \left(\omega t+\frac{\pi}{3}\right)\) (ii) \(I_0/\sqrt{2}\)
(c) \(I_0(\sin \omega t+\cos \omega t)\) (iii) \(I_0e\)
(d) \(I=I_0(e)\) (iv) \(I_0/2\sqrt{2}\)
 
A B C D
1. (iv) (ii) (i) (iii)
2. (iv) (ii) (iii) (i)
3. (ii) (iv) (iii) (i)
4. (ii) (iv) (i) (iii)
Subtopic:  RMS & Average Values |
 65%
From NCERT
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The primary and secondary coils of a transformer have \(50\) and \(1500\) turns respectively. If the magnetic flux \(\phi\) linked with the primary coils is given by \(\phi=\phi_0+4t\), where \(\phi\) is in webers, \(t\) is time in seconds, and \(\phi_0\) is a constant, the output voltage across the secondary coil is:
1. \(120\) V 2. \(220\) V
3. \(30\) V 4. \(90\) V
Subtopic:  Transformer |
 83%
From NCERT
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The primary winding of a transformer has \(500\) turns whereas its secondary has \(5000\) turns. The primary is connected to an AC supply of \(20\) V, \(50\) Hz. What will be the output of the secondary transformer?
1. \(200\) V, \(50\) Hz
2. \(2\) V, \(50\) Hz
3. \(200\) V, \(500\) Hz
4. \(2\) V, \(5\) Hz
Subtopic:  Transformer |
 83%
From NCERT
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If \(R\) and \(L\) are resistance and inductance of a choke coil and \(f\) is the frequency of current through it, then the average power of the choke coil is proportional to:
1. \(R ~\)
2. \(\frac{1}{f^2}\)
3. \(\frac{1}{L^2}\)
4. All of these

Subtopic:  Power factor |
 64%
From NCERT
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In the network shown below what is the reading of the AC voltmeter?
        
1. Zero 2. \(100\) V
3. \(200\) V 4. \(500\) V
Subtopic:  Different Types of AC Circuits |
From NCERT
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The power factor of the given circuit is:
             

1. \(1 \over 2\) 2. \(1 \over \sqrt2\)
3. \(\sqrt3 \over 2\) 4. \(0\)
Subtopic:  Power factor |
 82%
From NCERT
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The power factor of a series \(LCR\) circuit in resonance condition is:
1. zero 2. \(\dfrac{1}{2}\)
3. \(\dfrac{1}{\sqrt{2}}\) 4. \(1\)
Subtopic:  Power factor |
 80%
From NCERT
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What is the instantaneous power of a resistor having resistance \(R\) across an AC supply of \(E= E_0\sin(\omega t)\)?
1. \(\dfrac{E_{0}^{2}}{R} \sin^{2}\omega t\) 2. \(\dfrac{E_{0}^{2}}{R}\cos^{2}\omega t\)
3. \(\dfrac{E_{0}^{2}}{R}\) 4. \(\text{zero}\)
Subtopic:  Power factor |
 55%
From NCERT
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