Name an electromagnetic wave which is used in the radar system used in aircraft navigation. Give another use of the wave.

Radar systems are used to find out the correct position of the aircraft taken off or enemy aircraft position to protect the country from attack.

So, an electromagnetic wave in such a way that it can give precise position.

So,the microwave as an electromagnetic wave because it has larger wavelength (λ) and thus lower frequency (υ)

Because 

And the wave which has higher wavelength or lower frequency can be received by radar without any much deviation and position of aircraft could be found out.

Correct answer is microwave.

Microwave is also used in the microwave oven, which is used to cook food and also used to disinfect the kitchen items.