Question
Which has more luminous efficiency
✓
Answer
(b) Luminous efficacy is a measure of how well a light source produces visible light. It is the ratio of luminous flux to power, measured in lumens per watt in SI.Luminous efficacy can be normalized by the maximum possible luminous efficacy to a dimensionless quantity called luminous efficiency.
Luminous efficiency for the same power supply, $40 W$ fluorescent tube gives more light. Hence, $40 \mathrm{W}$ fluorescent tube has greater.
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