The principle of superposition states that when two or more waves meet, the resulting displacement is the algebraic sum of the individual displacements.
Stationary waves are formed by the superposition of two progressive waves with the same frequency and amplitude traveling in opposite directions.
Nodes are points of zero displacement in a stationary wave, while antinodes are points of maximum displacement.
Wavelength can be determined by measuring the distance between consecutive nodes or antinodes.
8.2 Diffraction:
Diffraction refers to the bending and spreading of waves as they encounter an obstacle or pass through an aperture.
Diffraction experiments demonstrate the qualitative effect of the gap width relative to the wavelength of the wave.
For example, water waves in a ripple tank can exhibit diffraction patterns when they encounter a barrier with an aperture.
8.3 Interference:
Interference occurs when two or more waves combine to form regions of constructive and destructive interference.
Interference experiments demonstrate the behavior of waves interfering with each other, such as water waves, sound waves, light waves, and microwaves.
Interference fringes, which are regions of constructive and destructive interference, can be observed under certain conditions.
The conditions for observing two-source interference fringes include coherent sources, a constant phase difference, and a narrow source width.
8.4 The diffraction grating:
The diffraction grating is a device that consists of a large number of equally spaced parallel slits or lines.
The grating equation, d sin θ = nλ, relates the wavelength (λ) of light to the separation between the grating lines (d), the order of the diffraction (n), and the angle of diffraction (θ).
A diffraction grating can be used to determine the wavelength of light by measuring the angle of diffraction.