CUET · PHYSICS · PYQ PAPER 2025
A light with an energy flux of 25 \( W/cm^2 \) falls on a non-reflecting surface at normal incidence. If the surface has an area of 50 \( cm^2 \) and the total energy falling on the surface is \( 10 \times 10^5 \) J. The total duration of time of the incidence of light is
- A 200 s
- B 400 s
- C 600 s
- D 800 s
Answer & Solution
Correct Answer
(D) 800 s
Step-by-step Solution
Detailed explanation
\( P = I \times A \) \( P = 25 \, W/cm^2 \times 50 \, cm^2 = 1250 \, W \) \( t = E / P \) \( t = (10 \times 10^5 \, J) / (1250 \, W) = 800 \, s \)
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