Light incident normally completely |MODERNPHYSICJEEMAIN2019

JEE MAIN 2019

10-04-2019 S2

Question

Light is incident normally on a completely absorbing surface with an energy flux of 25 Wcm2. If the surface has an area of $25 \mathrm{~cm}^2$, the momentum transferred to the surface in 40 min time duration will be :

Select the correct option:

$3.5 \times 10^{-6} \mathrm{Ns}$

$6.3 \times 10^{-4} \mathrm{Ns}$

$5.0 \times 10^{-3} \mathrm{Ns}$

$1.4 \times 10^{-6} \mathrm{Ns}$

✓ Correct! Well done.

✗ Incorrect. Try again or view the solution.

Solution

$\begin{aligned} & P=\frac{\Delta E}{C}=\frac{(25 \times 25) \times 40 \times 60}{3 \times 10^8} N-s \\ & =5 \times 10^{-3} N-s\end{aligned}$

Question Tags

JEE Main

Physics

Easy

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