Question

The momentum of a photon having frequency $1.0 \times 10^{15}$ $s ^{-1}$ is about

• A. $2.21 \times 10^{-11} kg \cdot m / s$
• B. $2.21 \times 10^{-27} kg \cdot m / s$
• C. $2.21 \times 10^{-19} kg \cdot m / s$
• D. $6.63 \times 10^{-19} kg \cdot m / s$

Answer 1

Answer: (B)

$P=\frac{h}{\lambda}=\frac{h}{C} \times v$

$=\frac{\left(6.6 \times 10^{-34} \,Js \right)\left(10^{15} s ^{-1}\right)}{\left(3 \times 10^{8} \,ms ^{-1}\right)}$

$=2.21 \times 10^{-27}\, kg \cdot m / s$