Lets do a physics question (a level)

Lets do a physics question (a level)

welcome back

The question is as follows

Q:A laser emits light of wavelength 600 nm
. What is the distance, expressed as a number of wavelengths, travelled by the light in one second?

 We know that

 1 nm=10^-9m
 therefore:                           600nm =6 x 10^-7m

 we also know that the speed of light is= 3 x 10 ⁸m/s
 so v= f x L

 note that the question asks for the frequency

so: f= 3 x 10⁸/6 x 10^-7 Hz
 the answer is f= 5 x 10¹⁴ Hz