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 $3.843\times 10^{14}s^-$.

Solution : Given,

wavelength = $7.80\times 10^2nm=7.80\times 10^2\times 10^{-9}m=7.80\times 10^{-7}m$                    $(1nm=10^{-9}m)$

Speed of light = $2.998\times 10^{8}m/s$

Formula used :

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

$\nu$ = frequency

$\lambda$ = wavelength

c = speed of light

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

$\nu=\frac{2.998\times 10^8m/s}{7.80\times 10^{-7}m}=0.3843\times 10^{15}s^-=3.843\times 10^{14}s^-$

Therefore, the frequency of light is $3.843\times 10^{14}s^-$.