If 2.5 × 10^{-6,} N average force is exerted by a light wave on a non-reflecting surface of 30, cm

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11.Dual Nature of Radiation and matter

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If $2.5 \times 10^{-6\,} N$ average force is exerted by a light wave on a non-reflecting surface of $30\, cm ^{2}$ area during $40$ minutes of time span, the energy flux of light just before it falls on the surface is .................. $W / cm ^{2}$

(Round off to the Nearest Integer)

(Assume complete absorption and normal incidence conditions are there)

A

$36$

B

$16$

C

$30$

D

$25$

(JEE MAIN-2021)

Solution

$F=\frac{I A}{C}$

$I=\frac{F C}{A}=\frac{2.5 \times 10^{-6} \times 3 \times 10^{8}}{30}=25 W / cm ^{2}$

Standard 12

Physics

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