Electric Illumination MCQ PDF

41. Halogen lamps have the advantage(s) of

(a) reduced dimensions of the lamp.
(b) better color rendition and longer life (about 2,000 hours).
(c) high operating temperature with increased luminous efficiency.
(d) all of the above.

42. The filament of a GLS lamp is made of

(a) aluminium.
(b) tungsten.
(c) carbon.
(d) copper.

43. Which of the following is not the GLS lamp of the standard rating ?

(a) 15 W
(b) 40 W
(c) 75 W
(d) 100 W

44. The luminous efficiency of GLS lamps is normally in the range of lumens/watt.

(a) 100 to 150
(b) 75 to 100
(c) 50 to 75
(d) 10 to 18

45. Nitrogen or argon is filled in GLS lamps so as to

(a) retard evaporation of tungsten filament.
(b) improve efficiency.
(c) change the color of the light.
(d) reduce the glare.

46. In case of frosted GLS lamps, frosting of shell is done by

(a) acid etching.
(b) ammonia.
(c) ozone.
(d) salt water.

47. In case of GLS lamps the increase in supply voltage reduces

(a) power consumption.
(b) lumens output.
(c) life.
(d) efficiency.

48. Sodium vapor lamp needs an ionization voltage of about

(a) 5 V
(b) 20 V
(c) 50 V
(d) 100 V

49. The ignition voltage for a sodium lamp is about

(a) 100 – 125 V
(b) 200 – 240 V
(c) 300 – 400 V
(d) 400 – 600 V

50. When a sodium vapor lamp is switched on, initially the color is

(a) red.
(b) pink.
(c) yellow.
(d) blue.

51. The color of light given out by a sodium vapor discharge lamp is

(a) pink.
(b) bluish green.
(c) yellow.
(d) blue.

52. An auto-transformer used with a sodium vapor lamp should have

(a) high step-up ratio.
(b) high step-down ratio.
(c) high leakage reactance.
(d) high resistance.

53. Leak transformer in a sodium vapor lamp initially provides

(a) high current.
(b) low voltage.
(c) high voltage.

54. In a sodium vapor discharge lamp the neon gas

(a) changes the color of light.
(b) prevents vaporization of filament.
(c) acts as a shield around the filament.
(d) assists in developing enough heat to vaporize the sodium.

55. The capacitor is used in auto-transformer circuit of a sodium vapor lamp in order to

(a) regulate discharge voltage.
(b) improve the circuit power factor.
(c) control lamp illumination level.
(d) protect the lamp against over-voltage.

56. The sodium vapor lamp

(a) is only suitable for ac and so needs choke control.
(b) needs capacitor in its auto-transformer circuit to improve the power factor which is very low (about 0.3 lagging).
(c) comes up to its rated output in approximately 15 minutes.
(d) all of the above.

57. The luminous efficiency of a sodium vapor lamp is lumens per watt.

(a) 40 – 50
(b) 50 – 100
(c) 120 – 200
(d) 10 – 12

58. Phosphor zinc silicate produces light of

(a) pink color.
(b) green color.
(c) red color.
(d) yellow color.

59. A mercury vapor lamp gives light of

(a) pink color.
(b) yellow color.
(c) greenish-blue color.
(d) red color.

60. High pressure mercury vapor lamps

(a) are similar in construction to sodium vapor lamps.
(b) need 4 or 5 minutes to attain full brilliancy.
(c) are generally used for general industrial lighting, railway yards, work areas, shopping centers etc.
(d) all of the above.