A wave is a disturbance that transfers energy without transferring matter. 

• There are two types of waves - transverse and longitudinal waves.

  
  

-Transverse wave: the direction of vibration of particles of the medium is perpendicular to the direction of travel of the wave. 

Examples: electromagnetic waves. 

-Longitudinal wave: the direction of vibration of particles of the medium is parallel to the 

direction of travel of the wave. 

Examples: sound waves, seismic P waves. 

• Crest: This is the highest point on a wave above the equilibrium or rest position. 

• Trough: This is the lowest point on a wave below the equilibrium or rest position 

• Amplitude: This is the distance from the undisturbed position to the peak or trough of a wave, and it is measured in meters

• Wavelength: This is the distance from one point on the wave to the same point on the wave. 

• Frequency: This is the number of waves passing a point in a second. It is given the symbol f and measured in Hertz (Hz). 

• Wave Front: This is a line drawn to represent the peaks of a wave in two dimensions. 

Wave equation: Wave speed = Frequency x Wavelength

v = fλ 

v ∝ f 

v ∝ λ

Properties of waves 

• Reflection, refraction, and diffraction are properties of waves.

• Reflection is the bouncing back of light from a smooth surface, with the angle of incidence equal to the angle of reflection. 

• Refraction is the bending of light when it passes from one medium to another, due to a change in speed, and hence, wavelength.

• In shallow water, the wavelength decreases, so the speed also decreases. Frequency is fixed as it depends on the source of the wave.

• Diffraction is the spreading of waves around the edges of an obstacle/a gap (depends on the size of the gap and the size of the wavefront).

Factors affecting diffraction: 

Diffraction generally happens when the gap is smaller than the wavelength. As the gap becomes bigger, the effect gradually gets less pronounced until the case where the gap is very much larger than the wavelength. Then the waves no longer spread at all. 

• If the gap is small compared to the wavelength, then the wavefronts curve and spread more. 

• If the gap is big compared to the wavelength, then the wavefront remains almost straight except at the edges of the gap, where some curvature occurs around the edge. 

• If there is only one edge of the gap, then the wave would curve around that edge.

Written by Hiba Shakeel

Curated by Quinn Luong