2012
NEET
MCQ
AIPMT 2012 Prelims
The current $(I)$ in the inductance is varying with time according to the plot shown in figure.
Which one of the following is the correct variation of voltage with time in the coil ?
Which one of the following is the correct variation of voltage with time in the coil ?
A.
B.
C.
D.
2012
NEET
MCQ
AIPMT 2012 Prelims
In an electrical circuit R, L, C and a.c. voltage source are all connected in series. When L is removed from the circuit, the phase difference between the voltage and the current in the circuit is If instead, C is removed from the circuit, the phase difference is again. The power factor of the circuit is
A.
${1 \over 2}$
B.
${1 \over {\sqrt 2 }}$
C.
1
D.
${{\sqrt 3 } \over 2}$
2011
NEET
MCQ
AIPMT 2011 Mains
A coil has resistance 30 ohm and inductive reactance 20 ohm at 50 Hz frequency. If an ac source, of 200 volt, 100 Hz, is connected across the coil, the current in the coil will be
A.
2.0 A
B.
4.0 A
C.
8.0 A
D.
${{20} \over {\sqrt {13} }}A$
2011
NEET
MCQ
AIPMT 2011 Mains
The r.m.s. value of potential difference V shown in the figure is
A.
${{{V_0}} \over {\sqrt 3 }}$
B.
V0
C.
${{{V_0}} \over {\sqrt 2 }}$
D.
${{{V_0}} \over 2}$
2011
NEET
MCQ
AIPMT 2011 Prelims
An ac voltage is applied to a resistance R and an inductor L in series. If R and the inductive reactance are both equal to 3 $\Omega $, the phase difference between the applied voltage and the current in the circuit is
A.
$\pi /6$
B.
$\pi /4$
C.
$\pi /2$
D.
zero
2011
NEET
MCQ
AIPMT 2011 Prelims
In the ac circuit an alternating voltage e = $200\sqrt 2 $sin100t volts is connected to a capacitor of capacity 1 $\mu $F. The r.m.s. value of the current in the circuit is
A.
10 mA
B.
100 mA
C.
200 mA
D.
20 mA
2010
NEET
MCQ
AIPMT 2010 Mains
A condenser of capacity C is charged to a potential difference of V1. The plates of th condenser are then connected to an ideal inductor of inductance L. The current through the inductor when the potential difference across the condenser reduces to V2 is
A.
${\left( {{{C{{\left( {{V_1} - {V_2}} \right)}^2}} \over L}} \right)^{{1 \over 2}}}$
B.
${{C\left( {V_1^2 - V_2^2} \right)} \over L}$
C.
${{C\left( {V_1^2 + V_2^2} \right)} \over L}$
D.
${\left( {{{C\left( {V_1^2 - V_2^2} \right)} \over L}} \right)^{{1 \over 2}}}$
2010
NEET
MCQ
AIPMT 2010 Prelims
A 220 volt input is supplied to a transformer. The output circuit draws a current of 2.0 ampere at 440 volts. If the efficiency of the transformer is 80%, the current drwn by the primary windings of the transformer is
A.
3.6 ampere
B.
2.8 ampere
C.
2.5 ampere
D.
5.0 ampere
2010
NEET
MCQ
AIPMT 2010 Prelims
In the given circuit the reading of voltmeter V1 and V2 are 300 volts each. The reading of the voltmeter V3 and ammeter A are respectively
A.
150V, 2.2A
B.
220V, 2.2A
C.
220V, 2.0A
D.
100V, 2.0A
2009
NEET
MCQ
AIPMT 2009
Power dissipated in an LCR series circuit connected to an A.C. source of emf $\varepsilon $ is
A.
${{{\varepsilon ^2}\sqrt {{R^2} + {{\left( {L\omega - {1 \over {\omega }}} \right)}^2}} } \over R}$
B.
${{{\varepsilon ^2}\sqrt {{R^2} + {{\left( {L\omega - {1 \over {C\omega }}} \right)}^2}} } \over R}$
C.
${{{\varepsilon ^2}R} \over {\sqrt {{R^2} + {{\left( {L - {1 \over {C\omega }}} \right)}^2}} }}$
D.
${{{\varepsilon ^2}R} \over {\left[ {{R^2} + {{\left( {L\omega - {1 \over {C\omega }}} \right)}^2}} \right]}}$
2008
NEET
MCQ
AIPMT 2008
In an a.c. circuit the e.m.f. ($\varepsilon $) and the current
(i) at any instant are given respectively by
$\varepsilon $ = E0sin$\omega $t, $i$ = $I$0sin($\omega $t $-$ $\phi $)
The average power in the circuit over one cycle of a.c. is
(i) at any instant are given respectively by
$\varepsilon $ = E0sin$\omega $t, $i$ = $I$0sin($\omega $t $-$ $\phi $)
The average power in the circuit over one cycle of a.c. is
A.
${{{E_0}{I_0}} \over 2}\cos \phi $
B.
${{E_0}{I_0}}$
C.
${{{E_0}{I_0}} \over 2}$
D.
${{{E_0}{I_0}} \over 2}\sin \phi $
2007
NEET
MCQ
AIPMT 2007
A transformer is used to light a 100 W and 110 V lamp from a 220 V mains. If the main current is 0.5 amp, the efficiency of the transformer is approximately
A.
50%
B.
90%
C.
10%
D.
30%
2007
NEET
MCQ
AIPMT 2007
The primary and secondary coils of a transformer have 50 and 1500 turns respectively. If the magnetic flux $\phi $ linked with the primary coil is given by $\phi $ = $\phi $0 + 4t, where $\phi $ is webers, t is time in seconds and $\phi $0 is a constant, the output voltage across the secondary coil is
A.
120 volt
B.
220 volts
C.
30 volts
D.
90 volts.
2007
NEET
MCQ
AIPMT 2007
What is the value of inductance L for which the current is maximum in a series LCR circuit with C = 10 $\mu $F and $\omega $ = 1000 s$-$1 ?
A.
1 mH
B.
cannot be calculated unless R is known
C.
10 mH
D.
100 mH
2006
NEET
MCQ
AIPMT 2006
A coil of inductive reactance 31 $\Omega $ has a resistance of 8 $\Omega $. It is placed in series with a condenser of capacitative reactance 25 $\Omega $. The combination is connected to an a.c. source of 110 V. The power factor of the circuit is
A.
0.33
B.
0.56
C.
0.64
D.
0.80
2006
NEET
MCQ
AIPMT 2006
A transistor-oscillator using a resonant circuit with an inductor L (of negligible resistance) and a capacitor C in series produce oscillations of frequency $f$. If L is doubled and C is changed to 4C, the frequency will be
A.
$f/2$
B.
$f/4$
C.
$8f$
D.
$f/2$$\sqrt 2 $
2006
NEET
MCQ
AIPMT 2006
The core of a transformer is laminated because
A.
ratio of voltage in primary and secondary may be increased
B.
energy losses due to eddy currents may be minimised
C.
the weight of the transformer may be reduced
D.
rusting of the core may be prevented.
2005
NEET
MCQ
AIPMT 2005
In a circuit L, C and R are connected in series with an alternating voltage source of frquency $f.$ The current leads the voltage by 45o. The value of C is
A.
${1 \over {\pi f\left( {2\pi f\,L - R} \right)}}$
B.
${1 \over {2\pi f\left( {2\pi f\,L - R} \right)}}$
C.
${1 \over {\pi f\left( {2\pi f\,L + R} \right)}}$
D.
${1 \over {2\pi f\left( {2\pi f\,L + R} \right)}}$
2004
NEET
MCQ
AIPMT 2004
A coil of 40 henry inductance is connected in series with a resistance of 8 ohm and the combination is joined to the terminals of a 2 volt battery. The time constant of the circuit is
A.
5 seconds
B.
1/5 seconds
C.
40 seconds
D.
20 seconds
2002
NEET
MCQ
AIPMT 2002
For a series LCR circuit the power loss at resonance is
A.
${{{V^2}} \over {\left[ {\omega L - {1 \over {\omega C}}} \right]}}$
B.
${I^2}L\omega $
C.
${I^2}R$
D.
${{{V^2}} \over {C\omega }}$
2001
NEET
MCQ
AIPMT 2001
A capacitor of capacity C has reactance X. If capacitance and frequency become double then reactance will be
A.
4X
B.
X/2
C.
X/4
D.
2X
2001
NEET
MCQ
AIPMT 2001
The value of quality factor is
A.
${{\omega R} \over L}$
B.
${1 \over {\omega RC}}$
C.
$\sqrt {LC} $
D.
$L/R$