Question

What is the wavelength of violet light that has a frequency of 7.5x10^14

Answer 1

Λ= V/f 
but change it to represent the speed of light, c 
λ= c/f 
c = 3.00 x 10^8 m/s 
Plug in your given info and solve for λ(wavelength) 
λ= 3.00 x 10^8 m/s / 7.5 x 10^14 Hz
(3.00 x 10^8) / (7.5 x 10^14) = 300,000,000 / 750,000,000,000,000 = 0.0000004
Hope this helps :)

Answer 2

Wavelength of any wave = (speed of the wave) / (frequency)

Speed of light in vacuum = 3 x 10^8 m/s

Wavelength =  (3 x 10^8) / (7.5 x 10^14)  =  4 x 10^-7 m  (400 nanometers)