Utilization of Electrical energy

         Some  important  questions 

(20 . Mcq for Electrical engineering              students ,  ILLUMINATION)

1. The filament of a GLS lamp is made      of

(a) aluminium. (c) carbon

(b) tungsten.     (d) copper

2.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. 

3. 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

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

 (a) retard evaporation of tungsten                       filament.

(b) improve efficiency

 c) change the colour of the light

(d) reduce the glare.

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

   (a) acid etching .

   (b) ammonia

    (c) ozone

   (d) salt water

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

  (a) power consumption 

  (b) lumens output

  (c) life: 

(d) efficiency

7.Sodium vapour lamp needs an               ionisation voltage of about 

(a) 5 V. 

(b) 20 V. 

(C) 50 V. 

(d) 100 V

8. The ignition voltage for a sodium           lamp is about

(a) 100-125 V 

(c) 300-400 V

(b) 200-240 V 

(d) 400-600 V

9. When a sodium vapour lamp is               switched on initially the colour is

  (a) red.

  (b) pink. 

  (c) yellow. 

  (d) blue.

10. The colour of light given out by a           sodium vapour discharge lamp is

(a) pink

 (b) bluish green  

(c) yellow. 

(d) blue. 

11.An auto transformer used with             sodium vapour lamp should have

(a) high step-up ratio

 (b) high leakage reactance.

 (c) high step-down resistance.

(d) high efficiency

12.Leak transformer in a sodium                vapour lamp initially provides

     (b) low voltage

     (a) high current

      (c) high voltage,

13. In a sodium vapour discharge                 lamp the neon gas 

(a) changes the colour of light,

(b) prevents Vapourization of filament,

 (c) acts as a shield around the filament,

(d) assists in developing enough heat to               vapourize the sodium 

Q

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

(a) regulate discharge voltage

(b) improve the circuit power factor.

(c) control lamp illuminution level. 

(d) protect the lamp against overvoltage,

15.The sodium vapour lamp (a) is               only suitable for ac and so needs          choke control

(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

(d) all of the above.

16. The luminous efficiency of a                  sodium vapour lamp is....lumens           per watt

 (a) 40-50

 (b) 50-100

 (c) 120-200 

 (d) 10-12

17. Phosphor zinc silicate produces            light of 

(a) pink colour.

(b) red colour.

(c) green colour

(d) yellow colour,

18. A mercury vapour lamp gives                light o

(a) pink colour 

(b) yellow colour 

(c) greenish-blue colour 

(d) red colour

19. High pressure mercury vapour              lamps 

(a) similar in construction to sodium                  vapour lamps:

(b) need 4 or 5 minutes to attain full                   brilliancy

 (c) are generally used for general                         industrial lighting

        yards, work areas, shoping centres etc.

 (d) all of the above

20.In high pressure mercury vapour          lamps

 (a) the main electrodes are made of                      tungsten wire in from of helix

(b) the choke is provided to limit the                 current to a safe value.

(e) in addition to two main electrodes a             starting (auxiliary) elec trode is                     connected through a high resistance

(d) all of the above.