Ohms Law Objective Questions and Answers

In this article, we shared the ohms law objective questions and answers for electrical and electronics engineers.

Ohms Law Objective Questions

Ohms Law Objective Questions and Answers

The below list provides all the multiple-choice questions related to basics and examples of problems on ohms law.

Answers are available at the bottom of the article.

1. A closed switch has a resistance of

B)about 50 ohms
D)about 500 ohms

2. The resistance of a few meters of wire conductor in a closed electrical circuit is

B)practically zero
C)very high

3. For which of the following substances the temperature coefficient of resistivity is positive?


4. Which of the following materials has the least resistivity?


5. The resistance of a copper wire 200 m long is 21 ω.​

If its thickness (diameter) is 0.44 mm, its specific resistance is around

A)1.2 x 10-8 ​​ω-m
B)1.4 x 10-8 ​​ω-m
C)1.8 x 10-8 ​​ω-m
D)1.6 x 10-8 ​​ω-m

6. Temperature coefficient of resistance is expressed in terms of


7. Specific resistance of a conductor depends upon

A)dimensions of the conductor and composition of conductor material.
B)dimensions of the conductor.
C)composition of conductor material.
D)resistance of the conductor

8. Heat in a conductor is produced on the passage of electric current due to


9. Which resistor will be physically larger in size?

A)10ω, 50W
B)1kω, 1W
C)1Mω, 1/2W
D)100ω, 10W

10. A light bulb draws 300 mA when the voltage across it is 240 V.​

The resistance of the light bulb is

A)800 ω
B)600 ω
C)400 ω
D)1000 ω

11. A 3 ω resistor having 2 A current will dissipate the power of

A)6 watts
B)8 watts
C)2 watts
D)4 watts

12. With rise in temperature the resistance of semiconductors

C)remains constant
D)first increases and then decreases

13. Voltage dependent resistors are usually made from

D)silicon carbide

14. For determining the polarity of the voltage drop across a resistor, it is necessary to know the

A)value of emf in the circuit.
B)value of current.
C)direction of current flowing through the resistor.
D)value of resistor.

15. Three resistances of 10 ohms, 15 ohms, and 30 ohms are connected in parallel.​

The total resistance of the combination is

A)10 ohms
B)55 ohms
C)15 ohms
D)5 ohms

16. Which of the following materials possesses the least specific resistance?


17. The temperature coefficient of resistance of an insulator is

A)positive and independent of temperature.
B)positive and dependent on temperature
C)negative and dependent on temperature.
D)negative and independent of temperature.

18. Two resistors R1 and R2 give combined resistance of 4.5 ω when in series and 1 ω when in parallel, the resistances are

A)4 ω and 0.5 ω
B)1.5 ω and 3 ω
C)1 ω and 3.5 ω
D)2 ω and 2.5 ω

19. Conductance is reciprocal of


20. If the length of a wire of resistance R is uniformly stretched to n times its original value, its new resistance is

A)​​n R

21. Four wires of same material, the same cross-sectional area and the same length when connected in parallel give a resistance of 0.25 ω.​

If the same four wires are connected is series the effective resistance will be

A)4 ω
B)2 ω
C)1 ω
D)3 ω

22. Voltage dependent resistors are used

A)to supress surges
B)for inductive circuits
C)as heating elements
D)as current stabilizers

23. The resistance of a parallel circuit consisting of two branches is 12 ohms.​

If the resistance of one branch is 18 ohms, what is the resistance of the other?

A)36 ω
B)64 ω
C)48 ω
D)18 ω

24. In a series circuit with unequal resistances

A)the lowest resistance has the highest current
B)In a series circuit with unequal resistances
C)the lowest resistance has the highest voltage drop
D)the highest resistance has the highest voltage drop

25. Two resistances R1 and R2 are connected in series across the voltage source where R2 > R1. The largest drop will be across

A)either R1 or R2
C)none of these answers

26. If a wire conductor of 0.2 ohm resistance is doubled in length, its resistance becomes

A)0.4 ohm
B)1.0 ohm
C)0.8 ohm
D)0.6 ohm

27. A network consists of linear resistors and ideal voltage source.​

If the value of the resistors are doubled, then voltage across each resistor is

A)not changed.
D)increased four lines.

28. The specific resistance of all metals is most affected by

A)Degree of illumination
B)Applied magnetic field

29. A resistance having rating 10 ohms, 10 W is likely to be a

A)wire wound resistor
B)metallic resistor
C)variable resistor
D)carbon resistor

30. Four resistances 80 ω, 50 ω, 25 ω and R are connected in parallel.​

Current through 25 ω resistance is 4 A.​

Total current of the supply is 10 A.​

The value of R will be

A)40.25 ω
B)76.56 ω
C)66.66 ω
D)36.36 ω

31. A rheostat differs from a potentiometer in the respect that it

A)has lower wattage rating
B)has higher wattage rating
C)offers large number of tappings
D)has large number of turns

32. Two resistors are said to be connected in series when

A)both carry the same value of current
B)total current equals the sum of branch currents
C)same current passes in turn through both
D)sum of IR drops equals the applied e.m.f.

33. Which of the following statements is correct regarding resistance?

A)The resistance of a conductor is the hindrance by which the conductor opposes the flow of current through it.
B)The resistance of a wire does not depend upon its material.
C)The resistance of wire is independent of the temperature for most of the materials
D)None of these answers

34. With three resistances connected in parallel, if each dissipates 20 W the total power supplied by the voltage source equals

A)40 W
B)60 W
C)10 W
D)20 W

35. A thermistor has

A)negative temperature coefficient
B)zero temperature coefficient
C)positive temperature coefficient
D)variable temperature coefficient

36. Specific resistance of a substance is measured in


37. The resistance of two wires is 25 ω when connected in series and 6 ω when joined in parallel. The resistance of each wire is

A)10 ω, 15 ω
B)20 ω, 30 ω
C)5 ω, 10 ω
D)10 ω, 20 ω

38. With rise in temperature the resistance of pure metals

B)remains constant
D)first increases and then decreases

39. Resistance of a wire always increases if

A)temperature is reduced.
B)number of free electrons available become more.
C)number of free electrons available become less.
D)temperature is increased.

40. Varistors are

B)non-linear resistors
C)carbon resistors
D)resistors with zero temperature coefficient

41. In equal resistances are first connected in series and then connected in parallel.​

What is the ratio of the maximum to the minimum resistance?


42. Resistance of material always decreases if

A)temperature of material is decreased
B)temperature of material is increased
C)none of these answers
D)number of free electrons available become more

43. The resistance of a straight conductor does not depend upon its

C)Shape of cross-section

44. In a circuit containing two unequal resistors connected in parallel

A)The voltage drop is larger across larger resistances
B)The voltage drop is same across both the resistances
C)The current is larger in larger resistance
D)The current is same in both the resistors

45. The specific resistance of a wire depends upon

A)Its dimensions
B)Its length
C)Its cross-sectional area
D)Its material

46. The temperature coefficient of resistance of a wire is 0.0008°C.​

If the resistance of the wire is 8 ohm at 0°C, what is the resistance at 100°C?

A)8.08 Ohm.
B)7.92 Ohm.
C)8.64 Ohm.
D)7.20 Ohm

47. A current of 16 amperes divides between two branches in parallel of resistances 8 ohms and 12ohms respectively.​

The current in each branch is

B)6.4 A, 6.9 A
C)4.6A, 6.9A
D)6.4 A, 9.6 A

48. In an ordinary heater if the length of the coil is halved, then a given quantity of water will boil

A)More time
B)None of these answers
C)Less time
D)Same time

49. Twelve 1 ω resistance are used as edges to form a cube.​

The resistance between two diagonally opposite corners of the cube is

A)6/5 ω
B)1 ω
C)5/6 ω
D)3/2 ω

50. Which of the following is an ohmic conductor?

A)Thermionic valves

51. Which of the following quantities remain the same in all parts of a series circuit?


52. You have to replace 1500 ω resistor in radio.​ You have no 1500 ω resistor but have several 1000 ω ones which you would connect

A)two in parallel and one in series
B)three in parallel
C)three in series
D)two in parallel

53. An open resistor, when checked with an ohm-meter reads

A)high but within tolerance
C)low but not zero

54. Two copper conductors have equal length.​

The cross-sectional area of one conductor is four times that of the other.​

If the conductor having smaller cross-sectional area has a resistance of 40 ohms the resistance of other conductors will be

A)20 ohms
B)160 ohms
C)80 ohms
D)10 ohms

55. The insulation resistance of a cable of length 10 km is 1 Mega Ohm’s.​

For a length of 100 km of same cable, the insulation resistance will be

A)1 Mega Ohm
B)0.1 Mega Ohm
C)10 Mega Ohm
D)0.01 Mega Ohm

56. The temperature coefficient of resistance of some material is negative. The material is


57. The temperature coefficient of resistance of conductors is

C)none of these answers

58. Three resistances each of R Ω are corrected to form a triangle.​ The resistance between any two terminals will be

A)3/2 R Ω
B)3 R Ω
C)2/3 R Ω

59. In a circuit a 33 ω resistor carries a current of 2 A. The voltage across the resistor is

D)80 V

60. The example of non-ohmic resistance is

A)Carbon resistance
B)Copper wire
D)Tungsten wire

61. Reciprocal of specific resistance is

A)Conductive resistance
B)Specific conductance
C)Plate resistance
D)Conductive reactance

62. The resistance of a conductor varies inversely as

C)area of cross-section

63. How are 500 ω resistors connected so as to give an effective resistance of 750ω?

A)Three resistors of 500 ω each, in series.
B)Two resistors of 500 ω each, in parallel and the combination in series with another 500 ω resistor.
C)Three resistors of 500 ω each, in parallel
D)Two resistors of 500 ω each, in parallel.

64. Three parallel resistive branches are connected across a dc supply.​

What will be the ratio of the branch currents I1 : I2 : I3 if the branch resistances are in the ratio R1 : R2 : R3 : : 2 : 4 : 6 ?

A)2 : 4 : 6
B)3 : 2 : 6
C)6 : 2 : 4
D)6 : 3 : 2

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