Q.1
The core of any transformer is laminated so as to [ AIEEE 2003]
  • a) reduce the energy loss due to eddy currents
  • b) make it light weight
  • c) make it robust and strong
  • d) increases the secondary voltage
Q.2
Alternating current can not be measured by D.C. ammeter because [ AIEEE 2004]
  • a) average value of current for complete cycle is zero
  • b) A.C. changes direction
  • c) A.C. can not pass through D.C. Ammeter
  • d) D.C. Ammeter will get damaged
Q.3
In an LCR series a.c. circuit, the voltage across each of the components L, C and R is 50V. The voltage across the LC combination will be [ AIEEE 2004]
  • a) 100V
  • b) 50√2 V
  • c) 50 V
  • d) zero
Q.4
A coil having n turns and resistance RΩ is connected with a galvanometer of resistance 4RΩ This combination is moved in time t seconds from a magnetic field W1 weber to W2 weber. The induced current in the circuit is [ AIEEE 2004]
  • a)
    ch-18_qn-244choice_img_no1.png
  • b)
    ch-18_qn-244choice_img_no2.png
  • c)
    ch-18_qn-244choice_img_no3.png
  • d)
    ch-18_qn-244choice_img_no4.png
Q.5
In a uniform magnetic field of induction B a wire in the form of semicircle of radius r rotates about the diameter of the circle with an angular frequency ω. The axis of rotation is perpendicular to the field. If the total resistance of the circuit is R, the mean power generated per period of rotation is [ AIEEE 2004]
  • a) (Bπrω)2 / 2R
  • b) (Bπr2ω)2 / 8R
  • c) (Bπr2ω) / 2R
  • d) (Bπrω2)2 / 8R
Q.6
In a LCR circuit capacitance is changed from C to 2C. For the resonant frequency to remain unchanged, the inductance should be changed from L to [ AIEEE 2004]
  • a) L/2
  • b) 2L
  • c) 4L
  • d) L/4
Q.7
one conducting U tube can slide inside another as shown in figure, maintaining electrical contacts between the tubes. The magnetic field B is perpendicular to the plane of the figure. If each tube moves towards the other at a constant speed v, then the emf induced in the circuit in terms of B, l and V where l is the width of each tube will be [ AIEEE 2005]
ch-18_que_no-247_img_no1.png
  • a) - Blv
  • b) Blv
  • c) 2Blv
  • d) zero
Q.8
A metal conductor of length 1 m rotates vertically about one of its ends at angular velocity 5 radians per second. If the horizontal component of earth's magnetic field is 0.2×10-4T, then the emf developed between the two ends of the conductor is [ AIEEE 2004]
  • a) 5 mV
  • b) 50 µV
  • c) 5 µV
  • d) 50 mV
Q.9
The self inductance of the motor of an electric fan is 10H. In order to impart maximum power at 50Hz, it should be connected to a capacitance of [ AIEEE 2005]
  • a) 8µF
  • b) 4µD
  • c) 2µF
  • d) 1µF
Q.10
The phase difference between the alternating current and emf is π/Which of the following cannot be the constituent of circuit [ AIEEE 2005]
  • a) R,L
  • b) C alone
  • c) L alone
  • d) L, C
Q.11
A circuit has a resistance of 12Ω and an impedance of 15Ω. The power factor of the circuit will be [ AIEEE 2005]
  • a) 0.4
  • b) 0.8
  • c) 0.125
  • d) 1.25
Q.12
A coil of inductance 300mH and resistance 2Ω is connected to a source of voltage 2V. The current reaches half of its steady state value in [ AIEEE 2005]
  • a) 0.1 s
  • b) 0.05s
  • c) 0.3s
  • d) 0.15s
Q.13
Which of the following units denote the dimension ML2 / QWhere Q denotes electric charge? [ AIEEE 2006]
  • a) Wb/m2
  • b) Henry (H)
  • c) H/m2
  • d) Weber(Wb)
Q.14
The flux linked with coil at any instant 't' is given by φ = 10t2 - 50t +250 The induced emf at t = 3s is [ AIEEE 2006]
  • a) -190 V
  • b) -10 V
  • c) 10 V
  • d) 190 V
Q.15
An inductor (L = 100 mH) a resistor ( R = 100Ω) and a battery (E = 100 V) are initially connected in series as shown in figure. After a long time the battery is disconnected after short circuiting the point A and B. the current in the circuit 1 ms after the short circuit is [ AIEEE 2006]
ch-18_que_no-255_img_no1.png
  • a) 1/e A
  • b) e A
  • c) 0.1 A
  • d) 1 A
Q.16
In an a.c. circuit the voltage applied is E = Eosinωt. the resulting current in the circuit is I = Iosin( ωt - π/2). The power consumption in the circuit is given by [ AIEEE 2007]
  • a) P = √2 EoIo
  • b) P = (EoIo) / √2
  • c) P = zero
  • d) P = EoIo / 2
Q.17
An ideal coil of 10H is connected in series with a resistance of 5Ω and a battery of 5V. 2 second after the connection is made, the current flowing in ammeter in the circuit is [ AIEEE 2007]
  • a) (1 - e-1)
  • b) (1 - e)
  • c) e
  • d) e-1
Q.18
two coaxial solenoids are made by winding thin insulated wire over a pipe of cross-sectional area A = 10 cm2 and length = 20 cm. If one of the solenoid has 300 turns and other 400 turns, their mutual inductance is [ AIEEE 2008]
  • a) 2.4π ×10-5 H
  • b) 4.8π ×10-4 H
  • c) 4.8π ×10-5 H
  • d) 2.4π ×10-4 H
Q.19
An inductor of inductance L = 400 mH and resistor of resistance R1 = 2Ω are connected to a battery of emf 12V as shown in figure. The internal resistance of the battery is negligible. The switch S is closed at t=The potential drop across L as a function of time is [ AIEEE 2009]
ch-18_que_no-259_img_no1.png
  • a)
    ch-18_qn-259choice_img_no1.png
  • b)
    ch-18_qn-259choice_img_no2.png
  • c)
    ch-18_qn-259choice_img_no3.png
  • d)
    ch-18_qn-259choice_img_no4.png
Q.20
In an AC generator, a coil with N turns, all of the same area A and total resistance R, rotates with frequency ω in a magnetic field B. The maximum value of emf generated in the coil is [ AIEEE 2006]
  • a) NABRω
  • b) NAB
  • c) NABR
  • d) NABω
Q.21
A coil of self-inductance L is connected in series with a bulb B and an AC source. Brightness of the bulb decreases when
  • a) Frequency of the AC source is decreased
  • b) Number of turns in the coil is reduced
  • c) A capacitance of reactance XC = XL is included in the same circuit
  • d) An iron rod is inserted in the coil
Q.22
A resistance 'R' draws power 'P' when connected to an AC source. If an inductance is now placed in series with the resistance, such that the impedance of the circuit becomes 'Z', the power drawn will be
  • a) p
    ch-18_qn-262choice_img_no2.png
  • b)
    ch-18_qn-262choice_img_no3.png
  • c)
    ch-18_qn-262choice_img_no4.png
  • d)
Q.23
A series R-C circuit is connected to an alternating voltage source. Consider two situations :- (a) When capacitor is air filled. (b) When capacitor is mica filled. Current through resistor is i and voltage acrosscapacitor is V then :-
  • a) Va = Vb
  • b) Va < Vb
  • c) Va > Vb
  • d) ia > ib
Q.24
An inductor 20 mH, a capacitor 50 µF and a resistor40Ωare connected inseries across a source of emf V = 10 sin 340 t. The power loss in A.C. circuit is :-
  • a) 0.51 W
  • b) 0.47 W
  • c) 0.76 W
  • d) 0.89 W
Q.25
A small signal voltage V(t) = V0 sin ωt is applied across an ideal capacitor C :- ….[AIPMT 2015]
  • a) Current I (t), lags voltage V(t) by 90°.
  • b) Over a full cycle the capacitor C does not consume any energy from the voltage source.
  • c) Current I (t) is in phase with voltage V(t).
  • d) Current I (t) leads voltage V(t) by 180°.
Q.26
Which of the following combinations should be selected for better tuning of an L-C-R circuit used for communication ?
  • a) R = 15 Ω, L = 3.5 H, C = 30 µF
  • b) R = 25 Ω, L = 1.5 H, C = 45 µF
  • c) R = 20 Ω, L = 1.5 H, C = 35 µF
  • d) R = 25 Ω, L = 2.5 H, C = 45 µF
Q.27
The potential difference across the resistance, capacitance and inductance are 80V, 40V and 100V respectively in an L-C-R circuit. The power factor of this circuit is …[NEET II 2016]
  • a) 0.8
  • b) 1.0
  • c) 0.4
  • d) 0.5
Q.28
A 100Ω resistance and a capacitor of 100Ω reactance are connected in series across a 220V source. When the capacitor is 50% charged, the peak value of the displacement current is …[ NEET II-2015]
  • a) 4.4 A
  • b) 11√2 A
  • c) 2.2 A
  • d) 11 A
Q.29
Figure shows a circuit contains three identical resistors with resistance R = 9.0 Ω each, two identical inductors with inductance L = 2.0 mH each,and an ideal battery with emf ε = 18 V. The current'i' through the battery just after the switch closed is …. [ NEET 2017]
ch-18_que_no-269_img_no1.png
  • a) 2 mA
  • b) 0.2 A
  • c) 2 A
  • d) 0 ampere
Q.30
The supply voltage to a room is 120 V. The resistance of the lead wires is 6Ω. A 60 W bulb is already switched on. What is the decrease of voltage across the bulb, when a 240 W heater is switched on in parallel to the bulb ? .. [ IIT Mains 2013]
  • a) zero Volt
  • b) 2.9 Volt
  • c) 13.3 Volt
  • d) 10.3 Volt
0 h : 0 m : 1 s