NDA/NA Examination

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NDA/NA 2023 - II Solved Paper NDA/NA 2023 - I Solved Paper NDA/NA 2022 - II Solved Paper NDA/NA 2022 - I Solved Paper NDA/NA 2021 - II Solved Paper

Questions on Electricity and Magnetism

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NDA/NA 2023 - II Exam

1. The potential difference between the two end terminals of an electric heater is 220 V and the current through it is 0.5 A. What would be the current through the heater if the potential difference across the terminals of the heater is reduced to 120 V?

  1. 1.0 A
  2. 0.5 A
  3. 0.27 A
  4. 0.7 A

2. The heating element in an electric iron is usually made of

  1. Constantan
  2. Tungsten
  3. Nichrome
  4. Copper

3. Which one of the following graphs correctly represents the current (I) - voltage (V) variation for a rectangular piece of semiconductor wafer?

4. Ms. Rani decides to convert her AC generator into a DC generator. Which one of the following she would need to use?

    >
  1. A split-ring type commutator
  2. Slip rings and brushes
  3. A stronger magnetic field
  4. A rectangular wire loop

5. Which of the following statements are correct about the electrical resistance and resistivity of a wire?

  1. Both quantities depend on the area of cross-section of the wire
  2. Both depend on the temperature
  3. Resistance of the wire is directly proportional to the resistivity of the wire
  4. Resistivity of the wire is directly proportional to the length of the wire

Select the correct answer using the code given below:

  1. 1 and 2
  2. 1 and 3
  3. 2 and 3
  4. 2 and 4

6. Which of the following arrangement of resistors offers minimum effective resistance between points X and Y?

7. What will happen if a collection of positive and negative charges are passed at a high speed through a magnetic field which is perpendicular to the direction of motion of the charges? (Assume that both kind of charges are NOT going to recombine)

  1. Both kind of charges will stop moving
  2. Positive charges and negative charges will separate out
  3. Positive charges will stop but negative charges will continue moving uninterrupted
  4. Both kind of charges will keep moving uninterrupted

NDA/NA 2023 - I Exam

8. In an electric circuit, a wire of resistance 10 ohms is used. If this wire is stretched to a lenght double of its original value, the current in the circuit would become:

  1. half of its original value.
  2. double of its original value.
  3. one-fourth of its original value.
  4. four times of its original value.

9. What is the total resistance in the following circuit element?

  1. R/2
  2. 3R
  3. 3R/2
  4. 2R/3

10. An electric bulb is rated as 220 V and 80 W. When it is operated on 110 V, the power rating would be:

  1. 80 W
  2. 60 W
  3. 40 W
  4. 20 W

NDA/NA 2022 - II

11. The commercial unit of electrical energy is kilowatt-hour (kWh), which is equal to

  1. 3.6 x 106 J
  2. 3.6 x 103 J
  3. 103 J
  4. 1 J

12. Which one of the following statements regarding a current-carrying solenoid is not correct?

  1. The magnetic field inside the solenoid is uniform.
  2. The current-carrying solenoid behaves like a bar magnet.
  3. The magnetic field inside the solenoid increases with increase in current.
  4. If a soft iron bar is inserted inside the solenoid, the magnetic field remains the same.

13. An electric bulb is connected to 220 V generator. The current drawn is 600 mA. What is the power of the bulb?

  1. 132 W
  2. 13.2 W
  3. 1320 W
  4. 13200 W

14. A current of 0.6 A is drawn by an electric bulb for 10 minutes. Which one of the following is the amount of electric charge that flows through the circuit?

  1. 6 C
  2. 0.6 C
  3. 360 C
  4. 36 C

15. A DC generator works on the principle of

  1. Ohm's law
  2. Joule's law of heating
  3. Faraday's laws of electromagnetic induction
  4. None of the above

16. The presence of magnetic field can be determined using which one of the following instruments

  1. Ammeter
  2. Volltmeter
  3. Magnetic needle
  4. Motor

17. Which one of the following terms cannot represent electrical power in a circuit?

  1. VI
  2. I2/R
  3. I2R
  4. V2/R

18. In which one of the following devices, the light energy is converted into the electrical energy?

  1. Light-emitting diode
  2. Laser diode
  3. Solar cell
  4. Transistor

19. Which one of the following metals is most commonly used for making filament of incandescent electric bulbs?

  1. Aluminium
  2. Silver
  3. Copper
  4. Tungsten

20. A microphone converts

  1. electrical signals to sound waves
  2. sound waves to electrical signals
  3. microwave to sound waves
  4. sound waves to microwaves

NDA/NA 2022 - I

21. Which of the following statements correctly explains/explain the existence of a positive force between two electric charges?

  1. Both the charges are positive.
  2. Both the charges are negative.
  3. Both the charges are oppositely charged.

Select the correct answer using the code given below.

  1. 1 only
  2. 2 only
  3. 1 and 2 only
  4. 1, 2 and 3

22. An electric wire of resistance 50 ohm is cut into five equal wires. These wires are then connected in parallel. What is the equivalent resistance of this combination?

  1. 2 ohm
  2. 10 ohm
  3. 0.5 ohm
  4. 5 ohm

23. The electric field lines from an isolated positively charged conducting sphere are

  1. tangential to the conducting surface
  2. at right angles to the conducting surface and towards the centre of the sphere
  3. at any angle to the conducting surface
  4. at right angles to the conducting surface and outwards from the centre of the sphere

24. The frequency of an alternating current is 3 Hz. It implies that

  1. there are 6 cycles/s
  2. there are 3 cycles/s
  3. there are 2 cycles/s
  4. there is only 1 cycle/s

25. Which one of the following correctly represents the SI unit of resistivity?

  1. Ω
  2. Ω/m
  3. Ω cm
  4. Ω m

26. What is the current required to light a 60 W incandescent bulb in a domestic supply of 240 V?

  1. 0.5 A
  2. 0.25 A
  3. 1.0 A
  4. 5.0 A

27. The magnetic field produced by a current-carrying straight wire at a point outside the wire depends

  1. inversely on the distance from it
  2. directly on the distance from it
  3. inversely at short distances and directly at large distances from it
  4. directly on the distance (at short distances) and inversely on the distance (at long distances) from it

28. According to Fleming's right-hand rule, if the forefinger indicates the direction of magnetic field and thumb shows the direction of motion of conductor, then the stretched middle finger will predict the direction of

  1. force acting on the conductor
  2. electric field
  3. induced current
  4. current

29. Two resistors R1 and R2 arranged in parallel combination in an electrical closed circuit are made of the same material and of same thickness. If the length of R2 is twice the length of R1, then the total resistance R satisfies

  1. 3R = 2R1
  2. 3R = 2R2
  3. 2R = 3R1
  4. 2R = 3R2
NDA 2021 - II

30. Three equal resistors are connected in parallel configuration in a closed electrical circuit. The the total resistance in the circuit becomes

  1. one-third of the individual resistance.
  2. two-third of the individual resistance.
  3. equal to the individual resistance.
  4. three times of the individual resistance.

31. Imagine a current-carrying straight conductor with magnetic field of lines in anti-clockwise direction. Then the direction of current is determined by

  1. the Right-Hand Thumb rule and it would be in the downward direction.
  2. the Left-Hand Thumb rule and it would be in the downward direction.
  3. the Right-Hand Thumb rule and it would be in the upward direction.
  4. the Left-Hand Thumb rule and it would be in the upward direction.

32. The device used to produce electric current is known as

  1. motor
  2. generator
  3. ammeter
  4. galvanometer

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