Infrared radiation has wavelengths ranging from about 800 nm to 1 mm. what is the frequency of radiation of wavelength 960 nm? answer in units of s-1.

The correct answer to your question and how to solve it is

The relation between wavelength (λ) and the frequency of electromagnetic oscillation (f) is described by the following expression: λ=c/f, where c-is the speed of light in vacuum = 3*10^8 m/s

Derive f from above: f = c/λ. How to Calculate: λ=890nm = 890*10^-9m = 8.9*10^-7m

f = 3*10^8m/s Divided by 8.9*10^-7m = 0.34*10^15 s-1=3.4*10^14 s-1

So your Answer is: The frequency of radiation of wavelength 890 nm is 3.4*10^14s-1