1.The discharge lamp with the highest efficacy but the poorest colour rendering


is the

(a) high-pressure sodium lamp

(b) fluorescent lamp

(c) low-pressure sodium lamp

(d) high-pressure mercury lamp.

2. The high-pressure sodium lamp

(a) provides a pure white light output

(b) usually requires a high-voltage pulse to start it

(c) is never used for high-bay industrial lighting

(d) is the least efficient of all the discharge lamps.

3. The discharge lamps most used in outdoor advertising signs are

(a) high-voltage cold-cathode types

(b) high-pressure mercury types

(c) low-voltage hot-cathode types

(d) low-pressure mercury-vapour types.

4. The rapid flicker in the light output from discharge lamps which may make rotating machinery appear stationary is called

(a) rapid flicker (b) disability glare

(c) epilepsy (d) the stroboscopic effect

5.Use sketches to explain the meaning of the term ‘load curves’. Draw a typical load curve for a large industrial area for a cold winter day and account for the shape of the curve. Why may the curve show significant changes from one day to the next?