2000 General Studies, all questions
UPSC Prelims 2000 · General Studies
Question 100: Science and Technology
Fluorescent tubes are fitted with a choke. The choke coils
astep up the line voltage
bstep down the line voltage
creduce current in the circuit
dchoke low-frequency currents
AnswerThe answer is (c).
A fluorescent tube is run on alternating current, and the choke is an inductor of high self-inductance. Its reactance limits the current without much loss of power, unlike a resistor, which would waste energy as heat. At switch-on, it also gives a brief high-voltage kick that starts the discharge, but its steady job is to limit current.
Why each option is right or wrong
- (a) The choke gives only a momentary high-voltage kick at starting; it does not step up the line voltage in steady use.
- (b) It does not step down the line voltage.
- (c) Right: the choke reduces the current in the circuit.
- (d) It limits alternating current rather than choking low-frequency currents as such.
Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2000, General Studies. UPSC's own paper isn't online; the words are from a published compilation. The paper on upsc.gov.in.