Dual Nature Of Matter Question 7
Question 7 - 30 January - Shift 1
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 :
(1) $0.5 \times 10^{-17} kg m / s$
(2) $2 \times 10^{-17} kg m / s$
(3) $3 \times 10^{-17} kg m / s$
(4) $1 \times 10^{-17} kg m / s$
Show Answer
Answer: (2)
Solution:
Formula: De Broglie wavelength
Momentum $=\frac{\text{ Energy }}{C}$
Power $\times$ time
$C$
$=\frac{(20 \times 10^{-3} w)(300 \times 10^{-9} s)}{3 \times 10^{8} m / s}$
$=2 \times 10^{-17} kg-m / s$
