Reflection of waves

What happens when waves arrive at the boundary between 2 different substances?

1 or more of the things can happen: absorption, reflection, refraction and transmission.

What’s absorption?

The energy of waves is transferred to the energy stores of the substance they travel into (eg, when food’s heated in a microwave).

What’s reflection?

The waves bounce back.

What’s refraction?

The waves change speed and direction as they cross the boundary.

What’s transmission?

The waves carry on moving once they’ve crossed the boundary, but may be refracted.

What can ray diagrams be used?

To show what happens when a wave’s reflected at a surface.

How to draw a ray diagram fro reflection: (step 1)

Use a ruler to draw all lines for the rays.

How to draw a ray diagram fro reflection: (step 2)

Draw a single arrow on the rays to show the direction the wave is travelling.

How to draw a ray diagram fro reflection: (step 3)

Draw a dotted line at right angles to the surface at the point of incidence.

How to draw a ray diagram fro reflection: (step 4)

Label the normal, the angle of incidence and the angle of reflection.

What’s the angle of incidence?

Where the light is and is equal to the angle of reflection.