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question_answer1)
When 100 volts dc is supplied across a solenoid, a current of 1.0 amperes flows in it. When 100 volts ac is applied across the same coil, the current drops to 0.5 ampere. If the frequency of ac source is 50 Hz, then the impedance and inductance of the solenoid are [CPMT 1990]
A)
200 W and 0.55 henry done
clear
B)
100 W and 0.86 henry done
clear
C)
200 W and 1.0 henry done
clear
D)
100 W and 0.93 henry done
clear
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question_answer2)
In an LR-circuit, the inductive reactance is equal to the resistance R of the circuit. An e.m.f. \[E={{E}_{0}}\cos (\omega t)\] applied to the circuit. The power consumed in the circuit is [MP PMT 1997]
A)
\[\frac{E_{0}^{2}}{R}\] done
clear
B)
\[\frac{E_{0}^{2}}{2R}\] done
clear
C)
\[\frac{E_{0}^{2}}{4R}\] done
clear
D)
\[\frac{E_{0}^{2}}{8R}\] done
clear
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question_answer3)
One 10 V, 60 W bulb is to be connected to 100 V line. The required induction coil has self inductance of value \[(f=50\,Hz)\] [RPET 1997]
A)
0.052 H done
clear
B)
2.42 H done
clear
C)
16.2 mH done
clear
D)
1.62 mH done
clear
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question_answer4)
In the circuit given below, what will be the reading of the voltmeter [RPET 1996]
A)
300 V done
clear
B)
900 V done
clear
C)
200 V done
clear
D)
400 V done
clear
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question_answer5)
In the circuit shown below, what will be the readings of the voltmeter and ammeter [RPMT 1996]
A)
800 V, 2A done
clear
B)
300 V, 2A done
clear
C)
220 V, 2.2 A done
clear
D)
100 V, 2A done
clear
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question_answer6)
A bulb and a capacitor are connected in series to a source of alternating current. If its frequency is increased, while keeping the voltage of the source constant, then [Roorkee 1999]
A)
Bulb will give more intense light done
clear
B)
Bulb will give less intense light done
clear
C)
Bulb will give light of same intensity as before done
clear
D)
Bulb will stop radiating light done
clear
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question_answer7)
An alternating e.m.f. of angular frequency \[\omega \] is applied across an inductance. The instantaneous power developed in the circuit has an angular frequency [Roorkee 1999]
A)
\[\frac{\omega }{4}\] done
clear
B)
\[\frac{\omega }{2}\] done
clear
C)
\[\omega \] done
clear
D)
\[2\omega \] done
clear
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question_answer8)
The voltage of an ac source varies with time according to the equation \[V=100\sin \ 100\pi t\cos 100\pi t\] where \[t\] is in seconds and V is in volts. Then [MP PMT 1996; 2000]
A)
The peak voltage of the source is 100 volts done
clear
B)
The peak voltage of the source is 50 volts done
clear
C)
The peak voltage of the source is \[100/\sqrt{2}\]volts done
clear
D)
The frequency of the source is 50 Hz done
clear
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question_answer9)
The diagram shows a capacitor C and a resistor R connected in series to an ac source. \[{{V}_{1}}\] and \[{{V}_{2}}\] are voltmeters and A is an ammeter
Consider now the following statements I. Readings in A and V2 are always in phase II. Reading in V1 is ahead in phase with reading in V2 III. Readings in A and V1 are always in phase which of these statements are/is correct [AMU (Med.) 2001]
A)
I only done
clear
B)
II only done
clear
C)
I and II only done
clear
D)
II and III only done
clear
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question_answer10)
In the circuit shown in figure neglecting source resistance the voltmeter and ammeter reading will respectively, will be [KCET (Engg.) 2001]
A)
0V, 3A done
clear
B)
150V, 3A done
clear
C)
150V, 6A done
clear
D)
0V, 8A done
clear
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question_answer11)
The voltage of an ac supply varies with time \[(t)\] as \[V=120\sin 100\,\pi \,t\cos 100\pi \,t.\] The maximum voltage and frequency respectively are [MP PMT 2001; MP PET 2002]
A)
120 volts, 100 Hz done
clear
B)
\[\frac{120}{\sqrt{2}}\] volts, 100 Hz done
clear
C)
60 volts, 200 Hz done
clear
D)
60 volts, 100 Hz done
clear
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question_answer12)
In the circuit shown in the figure, the ac source gives a voltage \[V=20\cos (2000\,t).\] Neglecting source resistance, the voltmeter and ammeter reading will be [KCET (Engg.) 2002]
A)
0V, 0.47A done
clear
B)
1.68V, 0.47A done
clear
C)
0V, 1.4 A done
clear
D)
5.6V, 1.4 A done
clear
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question_answer13)
A telephone wire of length 200 km has a capacitance of 0.014 mF per km. If it carries an ac of frequency 5 kHz, what should be the value of an inductor required to be connected in series so that the impedance of the circuit is minimum
A)
0.35 mH done
clear
B)
35 mH done
clear
C)
3.5 mH done
clear
D)
Zero done
clear
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question_answer14)
In a certain circuit current changes with time according to \[i=2\sqrt{t}.\] r.m.s. value of current between \[t=2\] to \[t=4s\] will be
A)
\[3A\] done
clear
B)
\[3\sqrt{3}A\] done
clear
C)
\[2\sqrt{3}A\] done
clear
D)
\[(2-\sqrt{2})A\] done
clear
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question_answer15)
Match the following Currents r.m.s. values (1) \[{{x}_{0}}\sin \omega \,t\] (i) x0 (2) \[{{x}_{0}}\sin \omega \,t\cos \omega \,t\] (ii) \[\frac{{{x}_{0}}}{\sqrt{2}}\] (3) \[{{x}_{0}}\sin \omega \,t+{{x}_{0}}\cos \omega \,t\] (iii) \[\frac{{{x}_{0}}}{(2\sqrt{2})}\]
A)
1. (i), 2. (ii), 3. (iii) done
clear
B)
1. (ii), 2. (iii), 3. (i) done
clear
C)
1. (i), 2. (iii), 3. (ii) done
clear
D)
None of these done
clear
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question_answer16)
The reading of ammeter in the circuit shown will be
A)
2A done
clear
B)
2.4 A done
clear
C)
Zero done
clear
D)
1.7 A done
clear
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question_answer17)
An ac source of angular frequency w is fed across a resistor r and a capacitor C in series. The current registered is I. If now the frequency of source is changed to w/3 (but maintaining the same voltage), the current in then circuit is found to be halved. Calculate the ratio of reactance to resistance at the original frequency w [Roorkee 1996]
A)
\[\sqrt{\frac{3}{5}}\] done
clear
B)
\[\sqrt{\frac{2}{5}}\] done
clear
C)
\[\sqrt{\frac{1}{5}}\] done
clear
D)
\[\sqrt{\frac{4}{5}}\] done
clear
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question_answer18)
An LCR series circuit with a resistance of 100 ohm is connected to an ac source of 200 V (r.m.s.) and angular frequency 300 rad/s. When only the capacitor is removed, the current lags behind the voltage by \[{{60}^{o}}\]. When only the inductor is removed the current leads the voltage by \[{{60}^{o}}\]. The average power dissipated is
A)
50 W done
clear
B)
100 W done
clear
C)
200 W done
clear
D)
400 W done
clear
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question_answer19)
A virtual current of 4A and 50 Hz flows in an ac circuit containing a coil. The power consumed in the coil is 240 W. If the virtual voltage across the coil is 100 V its inductance will be
A)
\[\frac{1}{3\pi }\]H done
clear
B)
\[\frac{1}{5\pi }H\] done
clear
C)
\[\frac{1}{7\pi }H\] done
clear
D)
\[\frac{1}{9\pi }H\] done
clear
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question_answer20)
For a series RLC circuit R = XL = 2XC. The impedance of the circuit and phase difference (between) V and i will be
A)
\[\frac{\sqrt{5}R}{2},\,{{\tan }^{-1}}(2)\] done
clear
B)
\[\frac{\sqrt{5}R}{2},{{\tan }^{-1}}\left( \frac{1}{2} \right)\] done
clear
C)
\[\sqrt{5}{{X}_{C}},{{\tan }^{-1}}(2)\] done
clear
D)
\[\sqrt{5}R,\,{{\tan }^{-1}}\left( \frac{1}{2} \right)\] done
clear
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question_answer21)
In the adjoining ac circuit the voltmeter whose reading will be zero at resonance is
A)
V1 done
clear
B)
V2 done
clear
C)
V3 done
clear
D)
V4 done
clear
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question_answer22)
In the adjoining figure the impedance of the circuit will be
A)
120 ohm done
clear
B)
50 ohm done
clear
C)
60 ohm done
clear
D)
90 ohm done
clear
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question_answer23)
If \[i={{t}^{2}}\] \[0<t<T\] then r.m.s. value of current is
A)
\[\frac{{{T}^{2}}}{\sqrt{2}}\] done
clear
B)
\[\frac{{{T}^{2}}}{2}\] done
clear
C)
\[\frac{{{T}^{2}}}{\sqrt{5}}\] done
clear
D)
None of these done
clear
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question_answer24)
Is it possible
A)
Yes done
clear
B)
No done
clear
C)
Cannot be predicted done
clear
D)
Insufficient data to reply done
clear
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question_answer25)
In a series circuit \[C=2\mu F,\,L=1mH\] and \[R=10\,\Omega ,\]when the current in the circuit is maximum, at that time the ratio of the energies stored in the capacitor and the inductor will be
A)
1 : 1 done
clear
B)
1 : 2 done
clear
C)
2 : 1 done
clear
D)
1 : 5 done
clear
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