Current Electricity MCQs Quiz Multiple Choice Questions & Answers

1. If a power of 100 watt is being supplied across a potential difference of 200 V, current flowing is

1. 4.1666666666666664E-2
2. 20 A
3. 2A
4. 0.5 A

2. A 5A fuse wire can with stand a maximum power of 1W in circuit. The resistance of the fuse wire is:

1. 0.4 Ω
2. 0.04 Ω
3. 0.2 Ω
4. 5 Ω

3. A carbon resistance is having a following coding green, orange, black, gold. The resistance of resistor is

1. 53 x 10⁰ ± 10%
2. 53 x 10 ± 10%
3. 53 x 10⁰ ± 5%
4. 53 x 10¹ ± 5%

4. A cell of emf E is connected with an external resistance R, then p.d. across cell is V. The internal resistance of cell will be

1. (V-E)R/V
2. (V-E)R/E
3. (E-V)R/E
4. (E-V)R/V

5. A steady current flows in a metallic conductor of non-uniform cross-section. The quantities/quantity constant along the length of the conductor is/are

1. Current and drift speed
2. Current only
3. Current, electric field and drift speed
4. Drift speed only

6. A uniform w ire connected across a supply produces heat H per second. If wire is cut into three equal parts and all the parts are connected in parallel across the same supply, the heat produced per second will be :

1. 3 H
2. H3
3. H/9
4. 9 H

7. A wire of resistance 3 Ω is cut into three pieces, which are then joined to form a triangle. The equivalent resistance between any corners of the triangle is :

1. 1/2 Ω
2. 1/3 Ω
3. 2/3 Ω
4. 3/2 Ω

8. An electric heater is connected to the voltage supply. After few seconds, current gets its steady value then its initial current will be

1. slightly less than its steady current
2. zero
3. equal to its steady current
4. slightly higher than its steady current

9. An electric heating element consumes 500 W, when connected to a 100 V line. If the line voltage becomes 150 V, the power consumed Will be:

1. 1000 W
2. 1125 W
3. 500 W
4. 750 W

10. At what temperature will the resistance of a copper wire become three times its value at 0⁰C? (Temperature coefficient of resistance for copper = 4 x 10^-3 per^oC)

1. 500^oC
2. 550^oC
3. 400^oC
4. 450^oC

11. By increasing the temperature, the specific resistance of a conductor and semiconductor

1. Increases, decreases
2. Decreases for both
3. Increases for both
4. Decreases for both

12. Calculate the amount of charge flowing in 2 minutes in a wire of resistance 10 ? when a potential difference of 20 V is applied between its ends

1. 20 C
2. 4C
3. 120 C
4. 240 C

13. For a metallic wire, the ratio V/i (V = the applied potential difference, i = current flowing) is

1. Decreases as the temperature rises
2. Increases or decreases as temperature rises, depending upon the metal
3. Independent of temperature
4. Increases as the temperature rises

14. If a certain piece of copper is to be shaped into a conductor of minimum resistance, its length (L) and cross-sectional area shall respectively be :

1. 2L, 2A
2. 2l, A/2
3. L, 2A
4. L/2, 2A

15. If n cells each of emf e and internal resistance r are connected in parallel, then the total emf and internal resistance will be

1. n ε, r/n
2. n ε, nr
3. ε, r/n
4. ε, nr

16. In a potentiometer of 10 wires, the balance point is obtained on the 7th wire. To shift the balance point to 9th wire, we should

1. decrease resistance in series with the cell whose emf is to be measured.
2. increase resistance in series with the cell whose emf is to be determined.
3. decrease resistance in the main circuit.
4. increase resistance in the main circuit.

17. In a Wheatstone bridge if the battery and galvanometer are interchanged then the deflection in galvanometer will

1. change in opposite direction
2. none of these.
3. change in previous direction
4. not change

18. In a Wheatstone‘s bridge all the four arms have equal resistance R. If the resistance of the galvanometer arm is also R, the equivalent resistance of the combination as seen by the battery is

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

19. In an experiment with potentiometer, null point with a cell is found at 240 cm. When the cell is shunted with a resistance 2 Ω, the null point becomes 120 cm internal resistance of cell is :

1. 1 Ω
2. 12 Ω
3. 4 Ω
4. 2 Ω

20. In an experiment with potentiometer, null point with a cell is found at 240 cm. When the cell is shunted with a resistance 2 Ω, the null point becomes 120 cm internal resistance of cell is :

1. 1 Ω
2. 12 Ω
3. 4 Ω
4. 2 Ω

21. In parallel combination of n cells, we obtain

1. less voltage
2. less current
3. more voltage
4. more current

22. Kirchhoffs first and second laws for electrical circuits are consequences of:

1. conservation of electric charge
2. neither conservation of energy nor electric charge
3. conservation of energy
4. conservation of electrical charge and energy respectively

23. Kirchoff‘s first and second laws in the electricity are the laws respectively of

1. Mass and charge conservation
2. Charge and energy conservation
3. Energy and Momentum conservation
4. Momentum and charge conservation

24. Siemen is the unit of:

1. specific conductance
2. None of these
3. resistance
4. conductance

25. Suppose H1 is the heat generated per second in the filament of a 100 W, 250 V lamp and H2 is the heat generated in the filament of a 200 W, 250 V lamp. Then H1/H2 is equal to:

1. 2-Jan
2. 4-Jan
3. 1
4. 2

26. The charge flowing in a conductor varies with time as: q = αt +1/2 βt² + 16 γt3 Where α, β, γ are positive constants. Then the initial current (l) is given by the condition :

1. l = α^-1
2. None of these
3. l = α
4. l = α²

27. The drift velocity does not depend upon

1. Number of free electrons
2. Magnitude of the current
3. Cross-section of the wire
4. Length of the wire

28. The electric resistance of a certain wire of iron is R. If its length and radius are both doubled, then

1. The resistance will be doubled and the specific resistance will be halved
2. The resistance will be halved and the specific resistance will remain unchanged
3. The resistance will be halved and the specific resistance will be doubled
4. The resistance and the specific resistance, will both remain unchanged

29. The example of a non-ohmic resistance is:

1. carbon resistor
2. diode
3. copper wire
4. fi lament lamp

30. The internal resistance of a cell of emf 12 V is 5 x 10^-2C Ω. It is connected across an unknown resistance. Voltage across the cell, when a current of 60 A is drawn from it, is

1. 9 V
2. 6 V
3. 15 V
4. 12 V

31. The resistivity of alloy manganin is

1. Decreases with increase in temperature
2. Increases rapidly with decrease in temperature
3. Nearly independent of temperature
4. Increases rapidly with increase in temperature

32. The smallest resistance that can be obtained by the combination of n resistors each resistance r is :

1. nr
2. n²r
3. r/n
4. nr

33. The specific resistance of a rod of copper as compared to that of thin wire of copper is :

1. same
2. depends upon the length and area of cross-section of the wire
3. less
4. more

34. Two conductors of equal length and radii the ratio of 2 : 3 are; connected in parallel the source of electricity. The ratio of the velocity of electrons in the conductor be :

1. 1 : 1
2. 3 : 2
3. 2 : 3
4. 4 : 9

35. Two equal resistors are connected in series across a battery and consume a power of P. If these are connected in parallel, then the power consumed will be:

1. p4
2. P
3. 2P
4. 4P

36. Two wires of the same material are given. The first wire is twice as long as the second and has twice the diameter of the second. The resistance of the first will be

1. Equal to the second
2. Four times of the second
3. Twice of the second
4. Half of the second

37. When a metal conductor connected to left gap of a meter bridge is heated, the balancing point

1. remains unchanged
2. remains at zero
3. shifts towards right
4. shifts towards left

38. Which of the following has a negative temperature coefficient of resistance ?

1. Nichrome
2. Platinum
3. Tungsten
4. Carbon