Question

What is the frequency of an x-Ray with a wavelength of 1.15 times 10^-10

Answer 1

v = f 入 (velocity = frequency x wavelength) 
If we have the speed ( for wave in vacuum i.e. 3 x 10^8 m/s) 
Then the frequency of x-ray is 
(3 x 10^8) ÷(1.15 x 10^-10) = 2.61 x 10^18