An em wave has frequency 9.90×10^14 hz . what is its wavelength?
how would we classify it?

303.03 nm

ultraviolet region

Explanation:

f = frequency of the EM wave = 9.90 x 10¹⁴ Hz

λ = wavelength of the EM wave = ?

v = speed of EM wave = 3 x 10⁸ m/s

Using the equation

v = f λ

Inserting the values

3 x 10⁸ = (9.90 x 10¹⁴) λ

λ = 303.03 x 10⁻⁹ m

λ = 303.03 nm

The wavelength of the ultraviolet rays lies between 10-400 nm. hence the EM wave belongs to ultraviolet region

the answer would be c

c) up is the direction the magnetic force is acting on the charge.