Q. Determine the frequency of light wave?

Ans.

The wavelength of red light is 7.0 x 10^-7 m. What is the frequency?

 c = λv

The first thing to remember here is that the speed of light is pretty much a constant value. For our purposes we will always use the value 3.00 x 10⁸ m/s.

So far we know wavelength and speed, all we have to do is solve for frequency:

Notice how the units cancel leaving us with units of 1/s, for frequency.

Remember to round off to 2 significant digits:

Notice that frequency is a really big number because the wavelength was a very small number.