Question

the wave number of a beam of light is 400 cm . what is the wavelength of light in nanometer?

Answer 1

0.4 nanometer
Hope my answer would help uu

Answer 2

Answer: The wavelength of light is $2.5\times 10^4nm$

Explanation:

The relationship between wavelength and wave number is given by the equation:

$\bar{\nu}=\frac{1}{\lambda}$

where,

$\bar{\nu}$ = wave number = 400 cm

$\lambda$ = wavelength of light = ?

Putting values in above equation, we get:

$400=\frac{1}{\lambda}\\\\\lambda=2.5\times 10^{-3}cm$

Converting this value into nano meters, we use the conversion factor:

$1cm=10^7nm$

So, $2.5\times 10^{-3}\times 10^7=2.5\times 10^4nm$

Hence, the wavelength of light is $2.5\times 10^4nm$