Energy is caused when an object, such as a guitar string or a bell, vibrates. This energy is transferred to the air, causing the air to vibrate. Finally, the air transfers the energy to our eardrum, causing it to vibrate. Our brain transfers the vibrations of the eardrum into nerve impulses that tell your brain that you hear the sound. Light energy is produced by the vibration of electrically charged particles called photons. Photons travel extremely fast (300 million meters per second!) but have no mass. Unlike sound energy, which needs air to vibrate, light energy can travel through a vacuum. This is why we can see objects like stars or planets that are in outer space.

Electrical energy is the energy of moving electrons, those negatively charged subatomic particles. By causing electrons to move through a wire, we can use them to do work.

Light energy comes from

A
nerve impulses.

B
electrons.

C
an object vibrating.

D
photons.