Question

The laser in an audio CD player uses light with a wavelength of 7.80 x 10 to the 2nd nm. Calculate the frequency of this light?

Answer 1

Answer : The frequency of light is
`3.843* 10^(14)s^-`.

Solution : Given,

wavelength =
`7.80* 10^2nm=7.80* 10^2* 10^(-9)m=7.80* 10^(-7)m`
`(1nm=10^(-9)m)`

Speed of light =
`2.998* 10^(8)m/s`

Formula used :

`\\u=(c)/(\lambda)`

`\\u` = frequency

`\lambda` = wavelength

c = speed of light

Now put all the given values in above formula, we get

`\\u=(2.998* 10^8m/s)/(7.80* 10^(-7)m)=0.3843* 10^(15)s^-=3.843* 10^(14)s^-`

Therefore, the frequency of light is
`3.843* 10^(14)s^-`.