Answer:
Circles forming when a rock drops into a pool.
Step-by-step explanation:
Dispersion of light forming rainbow and X-ray usage are the examples of electromagnetic energy.
But when a rock drops into a pool it has some energy due to gravity. When it hits the surface of water it tries to penetrate through water thus removing certain amount of water from that place. As the energy moves away, it forms ripples ( waves).
Thus formation of circles by dropping a rock into pool is an example of mechanical energy, not electromagnetic energy.