How do electromagnetic waves cause changes in materials?

Answer 1

• low frequencies induce eddy currents in metals, heating them.
• high frequencies vibrate atoms themselves, heating the material
• higher frequencies trigger chemical changes.
• very high frequencies knock electrons out of atoms, creating reactive ions.

Answer 2

Electromagnetic waves are a means of transporting energy. See related links, below. In the section called Rationale, you can click on each type of electromagnetic wave and find information.

When you place food in the microwave, the water molecules absorb the energy. This causes the water molecules to rotate and vibrate at a higher velocity. Temperature measures average kinetic energy of the atoms. So, the temperature of the food increases.

When I sit in front of the infrared heater, my skin feels warmer. As the molecules in my skin absorb the energy of infrared wave, the kinetic energy of the molecules increases. So, the temperature of the skin increases.

In chemistry, we learn about electrons. The energy of visible light "excites" the electrons. This is how we see the colors of objects.

As you continue down the list, the energy of the electromagnetic wave increases. This means the electromagnetic waves become more dangerous. Ultraviolet radiation can cause skin cancer. When you get an x-ray, they cover the other parts of your body to protect them. Gamma radiation can actually damage the DNA in your cells.