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11.Dual Nature of Radiation and matter
medium
A small object at rest, absorbs a light pulse of power $20\,mW$ and duration $300\,ns$. Assuming speed of light as $3 \times 10^8\,m / s$. the momentum of the object becomes equal to $.........\times 10^{-17} kg\,m / s$
A
$0.5$
B
$2$
C
$3$
D
$1$
(JEE MAIN-2023)
Solution
Momentum $=\frac{\text { Energy }}{ C }$
$=\frac{\text { Power } \times \text { time }}{ C }$
$=\frac{\left(20 \times 10^{-3} w \right)\left(300 \times 10^{-9}\,s \right)}{3 \times 10^8 m / s }$
$=2 \times 10^{-17}\,kg – m / s$
Standard 12
Physics
