Quiz - physics - Alternating Current-PYQ

Q1. The r.m.s. value of potential difference V shown in the figure is Source: orcusprep.in

NEET Mains 2011

easy

\( V_0/\sqrt{3} \)

\( V_0 \)

\( V_0/2 \)

\( V_0/\sqrt{2} \)

Q2. In an A.C. circuit, \(I_{rms}\) and \(I_0\) are related as Source: orcusprep.in

AIPMT 1994

easy

\( I_{rms} = 2I_0 \)

\( I_{rms} = I_0/\sqrt{2} \)

\( I_{rms} = I_0 \)

\( I_{rms} = \sqrt{2}I_0 \)

Q3. Two cables of copper are of equal lengths. One of them has a single wire of area of cross-section A, while other has 10 wires of cross-sectional area A/10 each. Give their suitability for transporting A.C. and D.C. Source: orcusprep.in

AIPMT 1994

easy

only multiple strands for A.C., either for D.C.

only multiple strands for A.C., only single strand for D.C.

only single strand for D.C., either for A.C.

only single strand for A.C., either for D.C.

Q4. A coil of self-inductance L is connected in series with a bulb B and an AC source. Brightness of the bulb decreases when Source: orcusprep.in

NEET 2013

easy

a capacitance of reactance \( X_C = X_L \) is included in the same circuit.

an iron rod is inserted in the coil.

frequency of the AC source is decreased.

number of turns in the coil is reduced.

Q5. A series LCR circuit is connected to an ac voltage source. When L is removed from the circuit, the phase difference between current and voltage is \( \pi/3 \). If instead C is removed from the circuit, the phase difference is again \( \pi/3 \) between current and voltage. The power factor of the circuit is Source: orcusprep.in

NEET 2020

medium

zero

0.5

1.0

-1.0

Q6. A circuit when connected to an AC source of 12 V gives a current of 0.2 A. The same circuit when connected to a DC source of 12 V, gives a current of 0.4 A. The circuit is Source: orcusprep.in

Odisha NEET 2019

medium

series LR

series RC

series LC

series LCR

Q7. Which of the following combinations should be selected for better tuning of an L-C-R circuit used for communication ? Source: orcusprep.in

NEET-II 2016

easy

R = 20 Ω, L = 1.5 H, C = 35 mF

R = 25 Ω, L = 2.5 H, C = 45 mF

R = 15 Ω, L = 3.5 H, C = 30 mF

R = 25 Ω, L = 1.5 H, C = 45 mF

Q8. A series R-C circuit is connected to an alternating voltage source. Consider two situations : (i) When capacitor is air filled. (ii) When capacitor is mica filled. Current through resistor is \( i \) and voltage across capacitor is \( V \) then Source: orcusprep.in

NEET 2015

medium

\( i_a > i_b \)

\( V_a = V_b \)

\( V_a < V_b \)

\( V_a > V_b \)

Q9. 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 Source: orcusprep.in

AIPMT 2011

easy

\( \pi/6 \)

\( \pi/4 \)

\( \pi/2 \)

zero

Q10. 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 Source: orcusprep.in

AIPMT Mains 2011

medium

2.0 A

4.0 A

8.0 A

\( \frac{20}{\sqrt{13}} \) A

Q11. In the given circuit the reading of voltmeter \( V_1 \) and \( V_2 \) are 300 volts each. The reading of the voltmeter \( V_3 \) and ammeter A are respectively Source: orcusprep.in

AIPMT 2010

medium

150 V, 2.2 A

220 V, 2.2 A

220 V, 2.0 A

100 V, 2.0 A

Q12. What is the value of inductance L for which the current is maximum in a series LCR circuit with C = 10 mF and \( \omega = 1000 \,\text{s}^{-1} \)? Source: orcusprep.in

AIPMT 2007

easy

1 mH

cannot be calculated unless R is known

10 mH

100 mH

Q13. In a circuit L, C and R are connected in series with an alternating voltage source of frequency f. The current leads the voltage by \( 45^\circ \). The value of C is Source: orcusprep.in

AIPMT 2005

medium

\( \frac{1}{2\pi f (2\pi fL - R)} \)

\( \frac{1}{2\pi f (2\pi fL + R)} \)

\( \frac{1}{\pi f (2\pi fL - R)} \)

\( \frac{1}{2\pi f L + R} \)

Q14. The value of quality factor is Source: orcusprep.in

AIPMT 2000

easy

\( \frac{\omega L}{R} \)

\( \frac{1}{\omega R C} \)

\( \sqrt{LC} \)

\( L/R \)

Q15. An series L-C-R circuit is connected to a source of A.C. current. At resonance, the phase difference between the applied voltage and the current in the circuit, is Source: orcusprep.in

AIPMT 1994

easy

\( \pi \)

zero

\( \pi/4 \)

\( \pi/2 \)

Q16. An inductor 20 mH, a capacitor 100 \( \mu \)F and a resistor 50 \( \Omega \) are connected in series across a source of emf, \( V = 10 \sin(314t) \). The power loss in the circuit is Source: orcusprep.in

NEET 2018

medium

0.79 W

0.43 W

2.74 W

1.13 W

Q17. The potential differences across the resistance, capacitance and inductance are 80 V, 40 V and 100 V respectively in an L-C-R circuit. The power factor of this circuit is Source: orcusprep.in

NEET-II 2016

easy

0.4

0.5

0.8

1.0

Q18. An inductor 20 mH, a capacitor 50 \( \mu \)F and a resistor 40 \( \Omega \) are connected in series across a source of emf \( V = 10 \sin(340t) \). The power loss in A.C. circuit is Source: orcusprep.in

NEET-I 2016

medium

0.76 W

0.89 W

0.51 W

0.67 W

Q19. In an electrical circuit R, L, C and ac 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 \( \pi/3 \). If instead, C is removed from the circuit, the phase difference is again \( \pi/3 \). The power factor of the circuit is Source: orcusprep.in

NEET 2012

medium

\( 1/2 \)

\( 1/\sqrt{2} \)

1

\( \sqrt{3}/2 \)

Q20. The instantaneous values of alternating current and voltages in a circuit are given as \( i(t) = \frac{1}{2} \sin(100\pi t) \) ampere and \( e(t) = \sin(100\pi t + \frac{\pi}{3}) \) volt. The average power in watts consumed in the circuit is Source: orcusprep.in

NEET Mains 2012

medium

\( \frac{1}{4} \)

\( \frac{3}{4} \)

\( \frac{1}{2} \)

\( \frac{1}{8} \)

Q21. Power dissipated in an LCR series circuit connected to an A.C. source of emf \( \varepsilon \) is Source: orcusprep.in

AIPMT 2009

medium

\( \frac{\varepsilon^2 R}{R^2 + \left( \omega L - \frac{1}{\omega C} \right)^2} \)

\( \frac{\varepsilon^2}{R^2 + \left( \omega L - \frac{1}{\omega C} \right)^2} \)

\( \frac{\varepsilon R}{R^2 + \left( \omega L - \frac{1}{\omega C} \right)^2} \)

\( \frac{\varepsilon^2 R}{R + \left( \omega L - \frac{1}{\omega C} \right)} \)

Q22. In an a.c. circuit the e.m.f. (e) and the current (i) at any instant are given respectively by \( e = E_0\sin(\omega t) \) and \( i = I_0\sin(\omega t - \phi) \). The average power in the circuit over one cycle of a.c. is Source: orcusprep.in

AIPMT 2008

easy

\( \frac{E_0 I_0}{2}\cos\phi \)

\( E_0 I_0 \)

\( \frac{E_0 I_0}{2} \)

\( \frac{E_0 I_0}{2}\sin\phi \)

Q23. 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 Source: orcusprep.in

AIPMT 2006

easy

0.33

0.56

0.64

0.80

Q24. For a series LCR circuit, the power loss at resonance is Source: orcusprep.in

AIPMT 2002

easy

\( V^2 \left( \omega L - \frac{1}{\omega C} \right) \)

\( I^2\omega L \)

\( I^2 R \)

\( \frac{V^2}{\omega C} \)

Q25. In an a.c. circuit with phase voltage V and current I, the power dissipated is Source: orcusprep.in

AIPMT 1997

easy

V.I

depends on phase angle between V and I

\( \frac{1}{2}V.I \)

1

Q26. In an A.C. circuit, the current flowing is \( I = 5 \sin (100t - \pi/2) \) ampere and the potential difference is \( V = 200 \sin (100t) \) volts. The power consumption is equal to Source: orcusprep.in

AIPMT 1995

easy

20 W

0 W

1000 W

40 W

Q27. A condenser of capacity C is charged to a potential difference of \( V_1 \). The plates of the 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 \( V_2 \) is Source: orcusprep.in

NEET Mains 2010

medium

\( \sqrt{\frac{C}{L}}(V_1 - V_2) \)

\( \sqrt{\frac{C}{L}}\sqrt{V_1^2 + V_2^2} \)

\( \sqrt{\frac{C}{L}}\sqrt{V_2^2 - V_1^2} \)

\( \sqrt{\frac{C}{L}}\sqrt{V_1^2 - V_2^2} \)

Q28. A transistor-oscillator using a resonant circuit with an inductor L (of negligible resistance) and a capacitor C in series produces oscillations of frequency f. If L is doubled and C is changed to 4C, the frequency will be Source: orcusprep.in

AIPMT 2006

easy

\( f/2 \)

\( f/4 \)

8f

\( f/2\sqrt{2} \)

Q29. A transformer having efficiency of 90% is working on 200 V and 3 kW power supply. If the current in the secondary coil is 6 A, the voltage across the secondary coil and the current in the primary coil respectively are Source: orcusprep.in

AIPMT 2014

medium

300 V, 15 A

450 V, 15 A

450 V, 13.5 A

600 V, 15 A

Q30. The primary of a transformer when connected to a dc battery of 10 volt draws a current of 1 mA. The number of turns of the primary and secondary windings are 50 and 100 respectively. The voltage in the secondary and the current drawn by the circuit in the secondary are respectively Source: orcusprep.in

NEET Karnataka 2013

easy

20 V and 2.0 mA

10 V and 0.5 mA

Zero volt and therefore no current

20 V and 0.5 mA

Q31. 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 drawn by the primary windings of the transformer is Source: orcusprep.in

AIPMT 2010

medium

3.6 ampere

2.8 ampere

2.5 ampere

5.0 ampere

Q32. 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 in webers, t is time in seconds and \( \phi_0 \) is a constant, the output voltage across the secondary coil is Source: orcusprep.in

AIPMT 2007

medium

120 volts

220 volts

30 volts

90 volts

Q33. 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 Source: orcusprep.in

AIPMT 2007

easy

50%

90%

10%

30%

Q34. The core of a transformer is laminated because Source: orcusprep.in

AIPMT 2006

easy

ratio of voltage in primary and secondary may be increased

energy losses due to eddy currents may be minimised

the weight of the transformer may be reduced

rusting of the core may be prevented.

Q35. A step-up transformer operates on a 230 V line and supplies a load of 2 ampere. The ratio of the primary and secondary windings is 1 : 25. The current in the primary is Source: orcusprep.in

AIPMT 1998

easy

15 A

50 A

25 A

12.5 A

Q36. The primary winding of a transformer has 500 turns whereas its secondary has 5000 turns. The primary is connected to an A.C. supply of 20 V, 50 Hz. The secondary will have an output of Source: orcusprep.in

AIPMT 1997

easy

2 V, 50 Hz

2 V, 5 Hz

200 V, 50 Hz

200 V, 500 Hz.

Q37. Figure shows a circuit that contains three identical resistors with resistance \( R = 9.0 \,\Omega \) each, two identical inductors with inductance \( L = 2.0 \,\text{mH} \) each, and an ideal battery with emf \( \varepsilon = 18 \,\text{V} \). The current i through the battery just after the switch closed is Source: orcusprep.in

NEET 2017

easy

0.2 A

4 A

0 ampere

2 mA

Q38. 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 Source: orcusprep.in

AIPMT 2004

easy

5 seconds

1/5 seconds

40 seconds

20 seconds

Q39. In the circuit given in figure, 1 and 2 are ammeters. Just after key K is pressed to complete the circuit, the reading will be Source: orcusprep.in

AIPMT 1999

medium

zero in 1, maximum in 2

maximum in both 1 and 2

zero in both 1 and 2

maximum in 1, zero in 2.

Q40. When the key K is pressed at time t = 0, then which of the following statement about the current I in the resistor AB of the given circuit is true? Source: orcusprep.in

AIPMT 1995

hard

I oscillates between 1 mA and 2 mA

At t = 0, I = 2 mA and with time it goes to 1 mA

I = 1 mA at all t

I = 2 mA at all t.

Q41. The time constant of C-R circuit is Source: orcusprep.in

AIPMT 1992

easy

1/CR

C/R

CR

R/C

Q42. To an AC power supply of 220 V at 50 Hz, a resistor of 20 \( \Omega \), a capacitor of reactance 25 \( \Omega \) and an inductor of reactance 45 \( \Omega \) are connected in series. The corresponding current in the circuit and the phase angle between the current and the voltage is, respectively: Source: orcusprep.in

NEET 2025

medium

15.6 A and 30°

15.6 A and 45°

7.8 A and 30°

7.8 A and 45°

Q43. In an ideal transformer, the turns ratio is \( N_p / N_s = 1/2 \). The ratio \( V_s : V_p \) is equal to (the symbols carry their usual meaning) : Source: orcusprep.in

NEET 2024

easy

1 : 2

2 : 1

1 : 1

1 : 4

Q44. A 10\( \mu \)F capacitor is connected to a 210V, 50 Hz source as shown in figure. The peak current in the circuit is nearly (\( \pi \) = 3.14) : Source: orcusprep.in

NEET 2024

medium

0.58 A

0.93 A

1.20 A

0.35 A

Q45. An ac source is connected in the given circuit. The value of \( \phi \) will be : Source: orcusprep.in

NEET 2023

easy

60°

90°

30°

45°

Q46. The maximum power is dissipated for an ac in a/an: Source: orcusprep.in

NEET 2023

easy

resistive circuit

LC circuit

inductive circuit

capacitive circuit

Q47. Given below are two statements
Statement I : In an a.c circuit, the current through a capacitor leads the voltage across it.
Statement II : In a.c circuit containing pure capacitance only, the phase difference between the current and voltage is \( \pi \).
In the light of the above statements, choose the most appropriate answer from the options given below: Source: orcusprep.in

NEET 2022

easy

Statement I is incorrect but Statement II is correct

Both Statement I and Statement II are correct

Both Statement I and Statement II are incorrect

Statement I is correct but Statement II is incorrect

Q48. An inductor of inductance 2 mH is connected to a 220 V, 50 Hz ac source. Let the inductive reactance in the circuit is \( X_{ac} \). If a 220 V dc source replace the ac source in the circuit, then the inductive reactance in the circuit is \( X_{dc} \). \( X_{ac} \) and \( X_{dc} \) respectively are : Source: orcusprep.in

NEET 2022

easy

0.628 \( \Omega \), infinite

6.28 \( \Omega \), zero

6.28 \( \Omega \), infinite

0.628 \( \Omega \), zero

Q49. A standard filament lamp consumes 100 W when connected to 200 V mains supply. The peak current through the bulb will be : Source: orcusprep.in

NEET 2022

medium

2 A

0.707 A

1 A

1.414 A

Q50. A series LCR circuit with inductance 10 H, capacitance 10 \( \mu \)F, and resistance 50 \( \Omega \) is connected to an AC source of voltage, V = 200sin(100t) volt. If the resonant frequency of the LCR circuit is \( \nu_r \) and the frequency of the AC source is \( \nu \), then. Source: orcusprep.in

NEET 2022

medium

\( \nu_r = 100 \,\text{Hz}, \nu = 100 \,\text{Hz} \)

\( \nu_r = 100 \,\text{Hz}, \nu = 50/\pi \,\text{Hz} \)

\( \nu_r = 50/\pi \,\text{Hz}, \nu = 50/\pi \,\text{Hz} \)

\( \nu_r = 50/\pi \,\text{Hz}, \nu = 100 \,\text{Hz} \)

Q51. The peak voltage of the AC source is equal to Source: orcusprep.in

NEET 2022

easy

The rms value of the AC source

\( \sqrt{2} \) times the rms value of the AC source

\( 1/\sqrt{2} \) times the rms value of the AC source

The value of the voltage supplied to the circuit

Q52. A capacitor of capacitance 'C', is connected across an ac source of voltage V, given by V = \( V_0 \sin\omega t \). The displacement current between the plates of the capacitor, would then be given by : Source: orcusprep.in

NEET 2021

medium

\( I_d = V_0\omega C \sin\omega t \)

\( I_d = V_0\omega C \cos\omega t \)

\( I_d = V_0 \sin\omega t / (\omega C) \)

\( I_d = V_0\omega C \)

Q53. An inductor of inductance L, a capacitor of capacitance C, and a resistor of resistance 'R' are connected in series to an AC source of potential difference 'V' volts as shown in Fig. Potential difference across L, C, and R is 40 V, 10 V, and 40V, respectively. The amplitude of the current flowing through the LCR series circuit is \( 10\sqrt{2} \)A. The impedance of the circuit is: Source: orcusprep.in

NEET 2021

medium

4\( \Omega \)

5\( \Omega \)

4\( \sqrt{2} \) \( \Omega \)

5\( \sqrt{2} \) \( \Omega \)

Q54. A step-down transformer connected to an AC mains supply of 220 V is made to operate at 11 V, 44 W lamp. Ignoring power losses in the transformer, what is the current in the primary circuit? Source: orcusprep.in

NEET 2021

easy

2 A

4 A

0.2 A

0.4 A

Q55. A series LCR circuit containing a 5.0 H inductor, 80 \( \mu \)F capacitor, and 40 \( \Omega \) resistor is connected to a 230 V variable frequency AC source. The angular frequencies of the source at which power transferred to the circuit are half the power at the resonant angular frequency are likely to be Source: orcusprep.in

NEET 2021

hard

46 rad/s and 54 rad/s

42 rad/s and 58 rad/s

25 rad/s and 75 rad/s

50 rad/s and 25 rad/s

Q56. If \( Z_1 \) and \( Z_2 \) are the impedances of the given circuits (a) and (b) as shown in figures, then choose the correct option Source: orcusprep.in

NEET 2023

medium

\( Z_1 < Z_2 \)

\( Z_1 + Z_2 = 20 \,\Omega \)

\( Z_1 = Z_2 \)

\( Z_1 > Z_2 \)

Q57. For very high frequencies, the effective impedance of the circuit (shown in the figure) will be: Source: orcusprep.in

NEET 2023

easy

4 \( \Omega \)

6 \( \Omega \)

1 \( \Omega \)

3 \( \Omega \)

Q58. The net impedance of the circuit (as shown in the figure) will be Source: orcusprep.in

NEET 2023

medium

10\( \sqrt{2} \) \( \Omega \)

15 \( \Omega \)

5\( \sqrt{5} \) \( \Omega \)

25 \( \Omega \)

Q59. The current I in an A.C. circuit with inductance coil
varies with time according to the graph given below. Source: orcusprep.in

AIPMT 1994

easy

a

b

c

d

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Physics - Alternating Current-PYQ

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Physics - Alternating Current-PYQ

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