A certain part of the electromagnetic spectrum ranges from 200 nm to 400 nm. What is the highest frequency associated with this portion of the spectrum

1.5* 10¹⁵ Hz

Explanation:

In any electromagnetic wave (assuming it's propagating in vacuum), the propagation speed is just c, the speed of light.As in any wave, there exists a fixed relationship between speed (c), frequency (f) and  wavelength (λ), as follows:

       

Since c is an universal constant, we can see that there exists an inverse relationship between λ and f, so if the lower the wavelength, the higher the frequency.So, in this case, the highest frequency will be the one associated with the lowest wavelength, i.e., 200 nm.Solving for f from (1), replacing by the values, we get:

       

It equals just about 6,300 km per hour each day an week