The wave that has the longest wavelength and lowest frequency is?

The wave that has the longest wavelength and lowest frequency is Radio waves.

Explanation:

Radio waves are a type of electromagnetic wave that has wavelength higher than infra red waves. It has frequency in the range from 30 hertz to 300 Giga heartz. The speed of radio waves are almost equal to speed of light in vacuum and in other medium the speed of radio waves decreases. This decrease in speed of radio waves depends on the permeability of the medium

Radio waves are used in radio communication, RADAR, SONAR and in other wireless communication system. Radio waves are generally transmitted by radio transmitter and received by radio receiver.

The wavelength and frequency of radio waves are inversely proportional to each other. Thus, for maximum wavelength the frequency of radio waves is minimum.