Wave Phenomena (HL)

Simple Harmonic motion

Defining equation

displacement, velocity and acceleration

Kinetic and potential energy

Energy transfer

Period of pendulum and mass-spring

Single-slit diffraction

What is single slit diffraction

Diffraction: a wave phenomena that occurs when a wave comes in contact with an obstacle or a slit. 

Single slit diffraction describes how a wave passing through a slit is bent upon exiting the slit. When this new curved wave hits a wall, a single-slit diffraction pattern is seen.

The single pattern is described by:

Image result for single slit diffraction pattern

Single slit diffraction pattern explained

The shape and intensity plot of single slit diffraction is caused by an idea known as Huygens' principle. This principle says that at every point on an advancing wave front acts as the center of a new wavelet emanating from that point. Thus we can consider the slit has having a infinite number of secondary wave sources which can constructively and destructively interfere with each other, as shown below. 

Huygens–Fresnel principle - Wikipedia

Explanation of central maximum and first minimum

Because the distance between the screen and slit is so big compared to the size of the slit, the angle between a specific point on the screen and any secondary source is approximately equal. 

Single-slit diffraction formula

\(\theta = \frac{\lambda}{b} = \frac{wavelength}{slit diameter}\)

derivation of single slit equation

Since the first minimum is at a point where the path difference between to parallel paths is \(\frac{\lambda}{2}\), we can determine a relationship between the angle from the center, \(\lambda\) and b.

Single slit diffraction

Effect of slit width on single slit diffraction

Single slit diffraction with white light

White light is a combination of different wavelengths and so when it is incident with a single slit, each wavelength of light will have it's own interference pattern. 

Diffraction - The Gemology Project

Young's double slit Interference



Modulation of two-slit interference pattern by one-slit diffraction effect


Multiple slit diffraction

Thin film interference


The size of a diffracting aperture

Resolution and Rayleigh criterion 

Resolvance of diffraction gratings

Doppler effect

Doppler effect for sound and light waves

Situations involving doppler effect

Determining velocity


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