FILL IN THE BLANKS
1. Visible light has wavelength between 4000 A and 7500 A.
2. Human eye is most sensitive for a wave length of 5500.
3. The color corresponding to wavelength 5500 A is Yellow, Green.
5. Steradian is defined as the solid angle that subtends a surface on the sphere equivalent to the square of the radius.
6. Tungsten filament lamp has efficiency of the order of 12 lumens/watt.
7. Sodium lamp is only suitable for AC .
8. Sodium lamp gives monochromatic Yellow light.
9. The efficiency of sodium vapor lamp is around50 lumens/watt.
10. In mercury vapor lamp the harmful ultra-violet rays are absorbed by Outer bulb.
11. Power factor of fluorescent lamps is low.
12. Leak transformer for sodium vapor lamps acts a choke coil for limiting the Current
when the lamp starts conducting.
13. The light from a sodium lamp is nearly Monochromatic.
14. In a color corrected high pressure mercury vapor lamp, the outer glass envelope is coated with Fluorescent powder.
15. Candela is the unit of Luminous intensity.
16. Neon lamps arc basically Gas discharge lamps.
17. Glow lamps emit only a faint glow and arc used as indicating lamps on panels and appliances.
18. Mercury vapor lamp gives 2.5 times times higher light than incandescent lamp for the same
power consumption.
19. Intensity of light varies inversely as square of distance of an object from the light source.
20. Wavelength for green color lies between that for yellow and blue.
21. Melting point of tungsten is about 3400 0C.
22. The Yellow-Green radiation of 555 mμ wavelength creates the strongest impression.
23. One angstrom is the same as 10 -7 mm.
24. If luminous flux equal to one lumen impinges on an area of one square meter, the illumination is equal to One lux .
25. An object which appears red to the eyes reflects mainly the red radiation and a little of orange and yellow radiations.
26. translucent materials arc used as screening materials for light sources.
27. In GLS lamps button incorporates support wires.
28. In GLS lamps the cap is secured to the glass shell by cementing compound.
29. To increase the working temperature and efficiency small % of nitrogen gas is filled in Gas-filled lamps.
30. In GLS lamps the blackening of the lamp glass shells is due to the deposits of tungsten vapor.
No comments:
Post a Comment