Question

The velocity of light is $3.0\times {10}^{8}m{s}^{-1}$. Which value is closest to the wavelength in nanometres 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. $3.7\times {10}^1$

Answer 1

Answer: (A)

$3\times {10}^7$

Given,

$velocity=3\times {10}^{8}m/s$

$frequency=8\times {10}^{15}{s}^{-1}$

As we know ,

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

putting the values , in above equation , we get ;

$8\times {10}^{15}=\frac{3\times {10}^8}{\lambda }$

After calculating , we get

$\lambda =3\times {10}^7$ (approx)

Hence , option A is correct .