Question

The wave number of a wave of light is 400 cm what's the wavelength of the light in nanometres and find the frequency of light

Answer 1

A=wavelenght

1/A=400cm

1/A=4m

A=1/4m

A=0.25m

also

v=fA

v=3*10^8

f=v/A

f=3*10^8/0.25

f=12*10^8hertz

Answer 2

wave number = 1/wavelength

so, 400 = 1/x

x = 1/4

x = 0.25 m

1 m = 10tothepower9

x = 2.5 * 10tothepower8 or 250000000

for frequency,

use, c=mew*lemda

mew is frequency

mew=3*10tothepower8/2.5tothepower8

frequency = 1.2