Two different wave groups with the same height travel together in the same direction. The wavelength of one group is twice as long as the wavelength of the other group. A combined wave of extra height will be produced .

A combined wave of extra height will produce every other wave.

Explanation:

One wave Crest can catch up to another wave Crest if the group of waves are from different places.

Here the two group of waves have different wavelength but travelling together in the same direction so when they combine,they will produce every other wave.

when heated, the valance electrons increased their speed and transferred the heat from electron to electron.   i just took the test.