What is the frequency of ultraviolet light that has a wavelength of 253 nm?
a. 7.59 x 10 14 Hz  b. 2.56 x 10 15 Hz  c. 8.43 x 10 14 Hz  d. 1.19 x 10 15 Hz

Hi teatea!!

Letīs work!!!

Wavelength-Frequency Relationship:
The two basic quantitites which describe a light wave are the
frequency f, of the wave (usually given in hertz, HZ, or cycles per
second), and the wavelength, w . These quantities are related to each
other and to the speed of light c, by:
w . f = c       or the equivalent     f = c / w 

Using this formula you can easily see that the correct answer is d:

c = 300,000 km/s = 3 x 10^5 km/s = 3 x 10^5 x (10^3) m/s (because 1km
= 10^3 m)
  = 3 x 10^8 m/s
and
1 nm = 10^-9 m ; 
then if w = 253 nm = 253 x 10^-9 m = 2.53 x 10^-7 m  we have:

f = c/w = (3 x 10^8 m/s)/ (2.53 x 10^-7 m) = 1.19 x 10^(8+7)[1/s] =
  = 1.19 x 10^15 Hz.

I hope this helps you.
If you need a clarification, please post a request for it.

Best regards.
livioflores-ga