Q.1.
The average power dissipation in a pure capacitor in AC circuit is [ MPMT 1998]
-
20%
a) ½ CV2
-
0%
b) CV2
-
20%
c) 2CV2
-
60%
d) zero
Q.2.
In an A.C circuit with voltage V and current I, the power dissipated is [ CBSE 1997]
-
50%
a) VI
-
17%
b) VI/8
-
0%
c) VI / √
-
33%
d) depends on the phase difference between I and V
Q.3.
A choke is used in fluorescent tube to [ Raj.PMT 1996]
-
20%
a) increase current
-
40%
b) decrease current
-
40%
c) increase voltage momentary
-
0%
d) decrease voltage momentary
Q.4.
An AC source is connected to a resistive circuit. What is true of the following? [ CPMT 1985]
-
17%
a) current leads ahead of voltage in phase
-
33%
b) current lag behind of voltage in phase
-
33%
c) current and voltage are in same phase
-
17%
d) any of the above may be true depending upon the value of resistance
Q.5.
In the LCR series circuit the voltmeter and ammeter readings are :
-
33%
a) V = 100 Volts, I = 2 amp
-
50%
b) V = 100 volts, I = 5 amp
-
17%
c) V = 100 volts, I = 3 amp
-
0%
d) V = 100 volts, I = 1 amp
Q.6.
The number of turns in the coil of an AC generator is 5000 and the area of the coil is 0.25mThe coil is rotated at the rate of 100 cycles per sec in a magnetic field of 0.2 weber/mThe peak value of the emf generated is nearly [ AMU 1995]
-
25%
a) 786kV
-
25%
b) 440kV
-
25%
c) 220kV
-
25%
d) 157.1 kV
Q.7.
A 20 volt A.C is applied to a circuit consisting of resistance and a coil with negligible resistance. If the voltage across the rsistance is 12Volts, the voltage across the coil is [ Raj. PMT 1997]
-
40%
a) 16 volts
-
40%
b) 10 volts
-
20%
c) 8 volts
-
0%
d) 6 volts
Q.8.
A generator produces a voltage that is given by V = 240sin(120 t) volt, where t is in second. The frequency and rms voltage are [ MPPMT 1993]
-
25%
a) 60 Hz and 240 Volts
-
25%
b) 19 Hz and 120 Volts
-
25%
c) 19 Hz and 170 Volts
-
25%
d) 754 Hz and 170 Volts
Q.9.
An AC generator produced an output voltage. E = 170sin(377 t) volts, where t is in seconds. The frequency of AC voltage is [ MPPMT 1994]
-
25%
a) 50Hz
-
50%
b) 110Hz
-
25%
c) 60HZ
-
0%
d) 230HZ
Q.10.
An inductive circuit contains a resistance of 10Ω and an inductance of 2.0 henry. If an AC voltage of 120 Volts and frequency of 60Hz is applied to this circuit, the current in the circuit would be nearly [ CPMT 1990]
-
0%
a) 0.32 amp
-
40%
b) 0.16 amp
-
40%
c) 0.48 amp
-
20%
d) 0.80 amp
Q.11.
The number of turns in the primary and the secondary of a transformer are 1000 and 3000 respectively. If 80 volt A.C. is applied to the primary coil of the transformer, then the potential difference per turn of the secondary coil would be [ CPMT 1990]
-
25%
a) 240 Volts
-
25%
b) 2400 volts
-
25%
c) 0.24 volts
-
25%
d) 0.08volts
Q.12.
In LCR circuit having L = 8.0 henry, C= 0.5µF and R = 100Ω in series. the resonance frequency ( in per second) is [ CPMT 1990]
-
20%
a) 600 radian/sec
-
0%
b) 600 hertz
-
60%
c) 500 radian/sec
-
20%
d) 500 hertz
Q.13.
An alternating voltage is connected in series with resuistance R and an inductance L. IF the voltage across the resistance is 200 volts and across the inductance is 150 volts the applied voltage is [ CPMT 1990]
-
40%
a) 350 vol
-
20%
b) 250 volt
-
20%
c) 500 volt
-
20%
d) 300 volt
Q.14.
A coil having an inductance of 1/π H is connected in series with a resistance of 300Ω. If 20V, 200Hz, AC source is impressed across the combination, the phase angle between voltage and current is [ JIPMER 1998]
-
40%
a) tan-1(5/4)
-
0%
b) tan-1(4/5)
-
40%
c) tan-1(3/4)
-
20%
d) tan-1(4/3)
Q.15.
In an L-C circuit the phase difference between current I and voltage V is [ CPMT 1999]
-
20%
a) π/2
-
20%
b) 0
-
20%
c) -π/2
-
40%
d) π
Q.16.
In a series circuit: R = 300Ω, L = 0.9H, C=2.0µF and ω = 1000rad/s The impedance of the circuit is [ PMT 1995]
-
20%
a) 1300Ω
-
0%
b) 900Ω
-
60%
c) 500Ω
-
20%
d) 400Ω
Q.17.
Hot wire ammeter are used for measuring ..[ Raj.PMT 1997]
-
20%
a) d.c.only
-
20%
b) a.c. only
-
0%
c) neither d.c nor a.c.
-
60%
d) both a.c. and d.c.
Q.18.
For series LCR circuit, wrong statement is [ Raj.PMT 1997]
-
17%
a) Applied emf and potential difference across resistance are in same phase
-
0%
b) Applied emf and potential difference at inductor coil have phase difference of π/2
-
50%
c) Potential difference at capacitor and inductor have phase difference of π/2
-
33%
d) phase difference between the potential difference between resistance and capacitor is π/2
Q.19.
In an A.C. circuit, the instantaneous values of e.m.f and current are e = 200sin(314 t) volts and i=sin(314t+π/2) ampere. The average power consumed in watts is [ NCERT 1990]
-
0%
a) 200
-
50%
b) 100
-
25%
c) 0
-
25%
d) 25
Q.20.
In a choke coil the reactance is XL and resistance is R, then [ Raj.PMT 1996]
-
25%
a) XL = R
-
50%
b) XL > > R
-
25%
c) XL < < R
-
0%
d) XL = ∞
Q.21.
A coil of reactance XL is connected to an a.c. source in which the effective current is I. The coil is made from superconducting material and has no resistance. The rate at which power is dissipated in the coil is [ MPPMT 1999]
-
25%
a) 0
-
25%
b) IXL
-
25%
c) I2XL
-
25%
d) IXL2
Q.22.
In general, in an alternating current circuit: [ MPPMT 1994]
-
20%
a) the average value of current is zero
-
0%
b) the average value of the current is zero
-
40%
c) average power dissipation is zero
-
40%
d) the phase difference between voltage and current is zero
Q.23.
Which of the following plots may represent the reactance of a series LC combination? [ MPPMT 1999]
-
50%
a) a
-
50%
b) b
-
0%
c) c
-
0%
d) d
Q.24.
The p.d across an instrument in AC circuit of frequency f is V and the current flowing through it is I such that V = 5cos2πft volts and I = 2sin2πt amp. The power dissipated in the instrument is [ MPPMT 1999]
-
25%
a) zero watts
-
25%
b) 10 watts
-
50%
c) 5 watts
-
0%
d) 2.5 watts
Q.25.
A step up transformer operates on a 230V line and supplies a load of 2 Ampere. The ratio of the primary and secondary winding is 1:The current in primary is [ CBSE 1998]
-
0%
a) 15A
-
25%
b) 25A
-
75%
c) 12.5A
-
0%
d) 50A
Q.26.
Which of the following effects does an alternating current show [ JIMPER 1998]
-
0%
a) chemical effect
-
25%
b) magnetic effect
-
50%
c) heating effect
-
25%
d) all of the above
Q.27.
The north pole of long horizontal bar magnet is being brought closer to a vertical conducting plane along the perpendicular direction. The direction of the induced current in the conducting plane will be [ MPPMT 1994]
-
0%
a) horizontal
-
0%
b) vertical
-
50%
c) clock wise
-
50%
d) anticlockwise
Q.28.
You have two copper cables of equal length for carrying current. One of them has a single wire of area of cross-section A, the other has ten wires of cross-section A/10 each. Judge their suitability for transporting A.C. and DC [ CBSE 1994]
-
25%
a) only single strand for D.C either for A.C
-
25%
b) only single strand for A.C either for D.C
-
0%
c) either for D.C only multiple strands for A.C.
-
50%
d) Only single strand for D.C. only multiple strands for A.C.
Q.29.
A conducting wire is stretched between the poles of a magnet. There is a strong uniform magnetic field in the region between the poles. If A.C. current I = Iosinωt is passed through the wire AB, then the wire will [ EAMCET 1985]
-
0%
a) remain stationary
-
25%
b) be pulled towards N-pole
-
25%
c) be pulled towards S-pole
-
50%
d) Vibrate with frequency (ω/2π)
Q.30.
In an A.C. circuit, the rms value of current Irms, is related to peak current Io by the relation [ CBSE 1994]
-
0%
a) Irms = 1 / πIo
-
50%
b) Irms =(1 /√2)Io
-
25%
c) Irms = √2 Io
-
25%
d) Irms = πIo