Refraction

Related links:

(AS level students) see Snell's Law and Composite block

Real and Apparent Depth

Refraction: change of wavespeed

Refraction through a rectangular glass block

Refraction of seismic waves

Refracting Telescope

Total Internal Reflection

Refraction is evidence of the wave nature of light - we can only explain refraction in terms of waves.

Wavespeed changes when a wave moves from one medium to another. (See here for more detail). That makes the wave refract.

Refraction of light

If a light ray speeds up it bends away from the normal - i.e. it makes a bigger angle with the normal than it did before - it swivels away from the normal.

... and if a ray slows down it bends towards the normal - i.e. it makes a smaller angle with the normal than it did before - it swivels towards the normal.

Refraction of sound

When you are dealing with 'sound' waves remember that sound waves travel fastest in dense media and slower in less dense ones. Therefore for sound waves refraction towards the normal indicates a speeding up of the wave! - see seismic waves

Now revise the topic from flash cards I have written for:

 

 

Refraction may be our route to invisibility...

LOJ October 2002 amended March 2003