Electromagnetic Waves

Which wave characteristic describes the product of the frequency and the wavelength?
Choose the correct answer from the alternatives given.
A plane electromagnetic wave of frequency 25 MHz travels in free space along x - direction. At a particular point in space and time, electric field B at this point is then
A plane electromagnetic wave of frequency $$25\ MHz$$ travels in free space along the x-direction. At a particular point in space and time, $$\vec { E } =6.3\hat { j } { V }/{ m }$$. What is $$\vec {B}$$ at this point?
If the wavelength of red light in air is $$7500$$ $$\overset{o}{A}$$, then the frequency of light in air is ___________.
According to the electromagnetic spectrum. Which of the following is NOT a pure spectral colour?