An auditor measures 1000 lux in a warehouse aisle where 150 is required. The recommendation is
Answer: A
Nearly seven times the requirement is a large and immediate saving available by removing luminaires or switching alternate rows, and it costs almost nothing. Relamping a grossly over-lit space at the same output would waste most of the investment.
Please log in or register to report this question.
A relighting scheme is proposed on energy grounds alone in a printing inspection area. The point to check first is
Answer: B
Colour judgement is the whole purpose of such an area, and a high-efficacy lamp with poor rendering would make it unusable whatever it saved. The task requirement constrains the choice before any energy comparison is made.
Please log in or register to report this question.
Assertion: cleaning luminaires saves energy. Reason: a dirty luminaire consumes more electricity than a clean one.
Answer: C
The consumption is unchanged; what falls is the light delivered, so the same electricity buys less and the effective efficacy drops. Cleaning restores the output, which allows luminaires to be removed or dimmed and the saving then realised.
Please log in or register to report this question.
Assertion: replacing every lamp with the highest efficacy type available is the correct lighting measure. Reason: efficacy determines the energy consumed for a given light output.
Answer: D
Efficacy does determine the energy per lumen, which is why it matters, but colour rendering, dimming, restrike and the illuminance actually required all constrain the choice. Replacing lamps in an over-lit room also invests in light that should have been removed.
Please log in or register to report this question.
Comparing a relamping measure with a control measure in a space lit continuously through the shift, the relamping
Answer: A
Correct answer: saves throughout, while controls have no hours to remove
A control measure saves only the hours it can switch off, and in a continuously occupied space there are none. A more efficient lamp saves in every one of those hours. The two measures are therefore complementary rather than alternatives, and which one pays depends entirely on the occupancy pattern.
Please log in or register to report this question.
None of the following reduces lighting energy except
Answer: B
Where the measured level is well above the standard, switching rows off is an immediate saving at no cost. Raising the level and reverting to magnetic ballasts both increase consumption, and bare lamps cause glare and soil faster.
Please log in or register to report this question.
The luminous efficacy of an electric light bulb is measured in which one of the following units?
GATE XE - 2026,
Answer: A
Luminous efficacy is measured in lumen W-1.
Luminous efficacy is the luminous flux emitted (lumens) per watt of electrical power drawn. A filament lamp gives about 15 lm/W and an LED lamp well over 100 lm/W.
Lumen per square metre is lux, the unit of illuminance; lumen W-1 h-1 mixes in time, which efficacy does not involve; and the candela measures luminous intensity in a given direction, not total flux.
Please log in or register to report this question.
