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.

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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.

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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.

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

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

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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

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46. Ampere – hour is the unit of

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

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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

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

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

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49. Referring to the above Fig.1.16, the value of α50 will

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

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50. Referring to Fig. 1.17, the value of αo is

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

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51. Referring to Fig. 1.17, the value of R40 will be

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

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52. Referring to Fig. 1.17, 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

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53. The value of αo 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

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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

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

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

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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.

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

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

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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

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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

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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

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