what is the electromagnetic output of the low-pressure mercury discharge in a fluorescent lamp

1. A lighting track feeds seven 20W12 V tungsten–halogen lamps. The current

 

rating of a suitable transformer would be

(a) 1.7 A (b) 42 A (c) 11.7 A (d) 7 A

2. A manufacturer controls the colour of a tubular fluorescent lamp by

(a) varying the lamp voltage

(b) choice of the fluorescent powder coating the inside of the tube

(c) choice of choke rating

(d) filament current and temperature

3.The fluorescent-lamp circuit shown in Figure 12.21 is for a

(a) semi-resonant system (b) quick-start system

(c) compact lamp (d) switch-start system

4.The compact fluorescent lamp is much less expensive to operate than the filament lamp because

(a) its purchase cost is cheaper

(b) the light output is whiter

(c) it is heavier

(d) efficacy is greater and life is longer

5. The electromagnetic output of the low-pressure mercury discharge in a fluorescent lamp is

(a) pure white light

(b) a mixture of the colours of the visible spectrum

(c) likely to give a loud mains hum on any nearby radio receiver

(d) almost entirely invisible but is converted to visible light by the

fluorescent powder

6. The light output of a high-pressure mercury-vapour lamp is

(a) very low considering the high power input usually required

(b) largely in the green and yellow parts of the visible spectrum

(c) like evening sunlight

(d) pure red, so that the lamp is used mainly for signs.

 

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