Question

The value of Planck's constant (h) is $6.63\times {10}^{-34}Js$. The velocity of light is $3.0\times {10}^{8}m{s}^{-1}$. Which value is closest to the wavelength (in meters) of a quantum of light with frequency of $8\times {10}^{15}{s}^{-1}$?

• A. $3\times {10}^7$
• B. $2\times {10}^{-25}$
• C. $5\times {10}^{-18}$
• D. $3.75\times {10}^{-8}$

Answer 1

The correct option is D $3.75\times {10}^{-8}$

Given

Planck's constant $=6.63\times {10}^{–34}$Js

Speed of the light$=3\times {10}^8$ nms${}^{-1}$

Frequency of quanta$=8\times {10}^{15}$ s${}^{-1}$

We know that

$v=\frac{c}{\lambda }$

$v=\frac{3\times {10}^8}{8\times {10}^{+15}}=\frac{3}{8}\times {10}^{-7}$

$=3.75\times {10}^{-8}$

Hence, the correct option is $D$