Sun light falls normally on a surface of area 36 cm 2 and exerts an average force of 7 . 2 × 10 - 9 N within a time period of 20 minutes. Considering a case of complete absorption, the energy flux of incident light is

Question

Sun light falls normally on a surface of area 36 cm 2 and exerts an average force of 7 . 2 × 10 - 9 N within a time period of 20 minutes. Considering a case of complete absorption, the energy flux of incident light is, 25 . 92 × 10 2 W cm - 2, 8 . 64 × 10 - 6 W cm - 2, 6 . 0 W cm - 2, 0 . 06 W cm - 2

MARKS App · Accepted Answer

The radiation pressure in case of complete absorption is given by, P = I c . Therefore, the force will be, F = I c × A ⇒ I = F c A ⇒ I = 7 . 2 × 10 - 9 × 3 × 10 8 36 × 10 - 4 = 600 W m - 2 ⇒ I = 0 . 06 W cm - 2

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