why two objects transfer energy between each other with maximum efficiency only when they have the same resonant electromagnetic frequency

When two objects have the same resonant electromagnetic frequency, it means that they are vibrating at the same rate. This allows them to transfer energy between each other with maximum efficiency because they are able to resonate with each other.

When two objects have different frequencies, they may still be able to transfer energy between each other, but the efficiency of the transfer will be lower. This is because the vibrations of the two objects will not be in sync, and some of the energy will be lost as heat or sound.

In summary, having the same resonant electromagnetic frequency allows for efficient energy transfer because it ensures that the vibrations of the two objects are in sync, leading to minimal energy loss.