Electrical Test Questions and Answers

41. The example of non-ohmic resistance is

(i) copper wire
(ii) carbon resistance
(iii) aluminium wire
(iv) tungsten wire.

42. A copper wire is stretched so that its length is increased by 0.1%. The change in its resistance is

(i) 0.3%
(ii) 0.4%
(iii) 0.2%
(iv) none of the above.

43. If an electric current is passed through a nerve, the man

(i) begins to laugh
(ii) begins to weep
(iii) is excited
(iv) becomes insensitive to pain.

44. Which one of the following is the best conductor of electricity ?

(i) silver
(ii) gold
(iii) copper
(iv) zinc.

45. The temperature co-efficient of resistance of a wire is 0.00125 per °C. At 300 K, its resistance is 1Ω. The resistance of the wire will be 2Ω at

(i) 1154K
(ii) 1100K
(iii) 1400K
(iv) 1127K

46. Ampere – hour is the unit of

(i) quantity of electricity
(ii) strength of current
(iii) power
(iv) energy.

47. The resistance of a conductor is 5 Ω at 50°C and 6 Ω at 100°C. What is its resistance at 0°C ?

(i) 1 Ω
(ii) 2 Ω
(iii) 3 Ω
(iv) 4 Ω

48. Fig. 1.16 shows the temperature/resistance graph of a conductor. The value of α_o is

(i) 0.005/°C
(ii) 0.04/^oC
(iii) 0.1/^oC
(iv) 0.4/°C

49. Referring to the above Fig.1, the value of α₅₀ will

be ..
(i) 0.005/^oC
(ii) 0.004/^oC
(iii) 0.4/^oC
(iv) 0.05/^oC

50. Referring to Fig. 2, the value of α_o is

(i) 1/30 per °C
(ii) 1/40 per °C
(iii) 1/1200 per °C
(iv) none of the above

51. Referring to Fig. 2, the value of R₄₀ will be

(i) 70 Ω
(ii) 40 Ω
(iii) 35 Ω
(iv) 50 Ω

52. Referring to Fig. 2, the value of α₄₀ will be

(i) 1/30 per °C
(ii) 1/70 per °C
(iii) 1/50 per°C
(iv) 1/1200 per °C

53. The value of α_o of a conductor is 1/236 per °C. The value of α₁₈ will be

(i) 1/218 per °C
(ii) 1/272 per °C
(iii) 1/254 per °C
(iv) none of the above

54. The value of α₂₅ of a conductor is 1/255 per °C. The value of α₂₀ will be

(i) 1/300 per °C
(ii) 1/230 per °C
(iii) 1/250 per °C
(iv) 1/265 per °C

55. The value of α₅₀ of a conductor is 1/230 per °C. The value of α_o will be

(i) 1/180 per °C
(ii) 1/280 per °C
(iii) 1/250 per °C
(iv) none of the above

56. The number of free electrons passing through the filament of an electric lamp in one hour when the current through the filament is 0.32 A will be

(i) 3 x 10²²
(ii) 2 x 10²⁶
(iii) 7.2 x 10¹⁹
(iv) 7.2 x 10²¹.

57. In which of the following substances the resistance decreases with increase in temperature?

(i) carbon
(ii) constantan
(iii) copper
(iv) silver

58. A wire having very high value of conductance is said to be

(i) very good conductor
(ii) moderately good conductor
(iii) insulator
(iv) none of the above

59. An electric heater is marked 2000 W, 200 V. The resistance of the coil is

(i) 0.1 Ω
(ii) 20 Ω
(iii) 1/20 Ω
(iv) 200 Ω

60. The current in a circuit having constant resistance is tripled. The power increases

(i) 1/9 times
(ii) 3 times
(iii) 9 times
(iv) 1/3 times