Q1. Study the frequency of the following electromagnetic radiations and select the correct relationship (‘>’ implies greater than):
I. : Infra-red
II. : Microwave
III. : Ultra-violet
(a) I > II > III
(b) III > I > II
(c) III > II > I
(d) II > III > I
(UPSC Prelims 1985)
Answer: (d) II > III > I
Explanation: In terms of frequency, the correct order is:
Microwave > Ultra-violet > Infra-red
This is because microwaves have higher frequency than infra-red, and ultra-violet lies above infra-red but below microwave in this context.
Q2. Which of the following groups of instruments is required to have communication line between two television relay centres ?
(a) Microwave link, telephone, booster relay, satellite
(b) Radio telescope, microwave link, booster relay, telephone
(c) Microwave link, booster relay, satellite
(d) None of the above
(UPSC Prelims 1987)
Answer: (c) Microwave link, booster relay, satellite
Explanation: Television relay centres use microwave links for signal transmission, booster relays to amplify signals, and satellites for long-distance communication. This combination ensures efficient and uninterrupted broadcasting.