Key Points When electromagnetic (EM) waves move from one medium to another, they can experience several interactions:

1. Transmission: The waves pass through the new medium.
2. Absorption: The waves are absorbed by the medium, converting their energy into other forms, like heat.
3. Reflection: The waves bounce back from the surface of the medium.
4. Refraction: The waves change direction as they enter the new medium due to a change in speed.

Refraction occurs when EM waves pass through different materials and their speed changes. While EM waves travel at the same speed in a vacuum, they slow down in materials like water, glass, or oil. This change in speed causes the waves to bend.

Wavefront diagrams visually represent how waves refract. When a wave enters a new medium, different parts of the wavefront enter at different times, causing the wave to bend. This bending occurs because the speed of the wave changes between the two media.

How It Works: As parts of the wavefront move at different speeds through the new medium, the entire wave changes direction. This bending effect can be shown in diagrams, illustrating the change in wave direction as it enters or exits the medium.