Wave Behaviour | Physics for GCSE/IGCSE - Year 11 PDF Download

Reflection, Refraction & Diffraction

• All waves, regardless of their type—transverse or longitudinal—can undergo reflection, refraction, and diffraction.

Reflection

• Reflection occurs when:
  • A wave hits a boundary between two media and does not pass through, but instead stays in the original medium.
• The law of reflection states:
  • The angle of incidence is equal to the angle of reflection.
• When waves hit an object, such as a barrier, they can be reflected:

When waves reflect off a barrier, the angle of reflection, r, is equal to the angle of incidence, i

Refraction

• When waves transition into another medium, their velocity may vary. This phenomenon, known as refraction, happens when:
• A wave crosses the boundary between two distinct transparent media, leading to a modification in speed.
• During refraction, besides altering speed, the wave also experiences:
  • A modification in wavelength (while frequency remains constant).
  • A deviation in direction.

• When waves decelerate, they will bunch up, resulting in a reduction in wavelength. Additionally, they will exhibit a slight inclination towards the normal direction.
• Conversely, when waves accelerate, they will disperse, leading to an increase in wavelength. Furthermore, they will show a slight deviation away from the normal direction.

Diffraction

• When waves traverse a narrow aperture, they disperse. This phenomenon is referred to as diffraction.

Factors Influencing Diffraction

• Diffraction generally occurs when the gap is smaller than the wavelength of the wave.
• As the gap widens, the effect becomes less noticeable.
• If the gap is much larger than the wavelength, the waves no longer spread out at all.

• Diffraction can also happen when waves encounter an edge.