4PH1
Reflection & Refraction
Waves · 1 question type
Exam Frequency Analysis
Past paper frequency (2018 to 2024)
This topic accounts for approximately 9% of your exam marks.
stable
Medium
Stable9%
Ray diagrams, Snell's Law and critical angle calculations appear regularly.
Light
- Light is part of the electromagnetic spectrum, so it is a transverse wave
- The vibrations of the electric and magnetic fields that make up the wave are at right angles to the direction the light is travelling
- Light can be reflected off a boundary and refracted through a boundary; both effects are covered in detail in the rest of this topic
Sound
- Sound waves are longitudinal waves; the air particles oscillate back and forth along the same line that the wave is travelling along
- Sound can also be reflected and refracted:
- the of a sound wave off a hard surface is called an echo
- sound refracts when it crosses between media of different densities (for example, layers of warm and cold air, or air and water), bending its direction of travel
Why both bend
- The same wave phenomena work for any wave type (water ripples, sound, light, microwaves, even seismic waves) because reflection and refraction depend on how a wave's speed changes when it meets a boundary, not on whether it is transverse or longitudinal