Interference of Light and Types of Superposition of Waves

Have you ever thought about what exactly happens when two waves travel in a medium meet? Do they pass through each other or bounce? Do these waves meet and affect the ending in any way? This chapter will discuss the interference of light and the superposition of waves.

The Principle of Superposition of Waves states that if waves travel through a medium, the waves are combined, or superposed, on top of each other.

What Is Wave Interference?

It is the phenomenon that occurs when two waves travelling in the same medium meet. The interference results in the medium taking shape. This is the effect of interference of two individual waves on the particles of the medium.

The speed of the wave varies in different media. Its frequency changes, but its velocity remains the same. As the frequency is the same, but the velocity is changing, it can be inferred that a wave’s wavelength changes when light travels in a different medium. In this case, the same wave, which is superimposed and travelling in the same direction, is a coherent addition; however, it is called incoherent addition in the case of a different wave.

What Is Interference of Light?

Interference means the superposition of two waves that forms a resultant wave of higher or lower frequency/ higher or lower velocity. Interference of light occurs when two or more waves travel in the same direction and encounter one another. This can result in signal degradation, and in some cases, it can destroy the waveform. It is essential to understand the principle of superposition of waves to avoid light interference.

What are the Conditions for Interference of Light?

The conditions for the interference of light are listed below.

•   The source of the wave should be coherent.
•   The coherent sources should maintain the same frequency (monochromatic source of light).
•   The waves must have equal amplitude.

Constructive Interference

Constructive interference occurs when two waves of the same frequency and amplitude overlap and produce a new third wave twice the frequency of the original two waves. This happens when you walk into a room and the sound of your footsteps mixes with the person next to you talking.

There are three main types of constructive interference: superposition, cancellation, and addition.

• Superposition occurs when two waves are combined, and the result is a new wave that is the sum of the two original waves.
• Cancellation happens when the two waves cancel out, producing no new wave.
• Addition happens when one wave pushes the other wave out of its normal range, creating a new, higher-frequency wave.

Destructive Interference

Destructive interference is the phenomenon that occurs when two waves of the same type interfere with each other. It is usually described in terms of waves of different types, such as sound waves and light waves. When these waves interact, they create a new kind of wave – a destructive interference wave.

Constructive and Destructive Interference

These occur when two waves (same length, amplitude and frequency) travel in a specific direction or the same direction. According to the superposition policy, the following wavelengths can be labelled:

y (x, t) = y m sin (kx-ωt) + y m sin (kx-ωt + ϕ) = 2 y m cos (ϕ / 2) sin (kx-ωt + ϕ / 2)

This wave has an amplitude dependent on section (ϕ). Therefore, when two waves are considered a phase (ϕ = 0), they interfere positively. In addition, the resulting waveguide has twice the amplitude of individual waves.

In contrast, when two waves have a cross-section (ϕ = 180), they interfere with damage and cancel each other.

Conclusion

The principle of superposition of waves states that when waves are in contact, they can still travel and spread out. This means that the waves can still add up, even if they are separate. They can form a wave of the lighter, lower or same amplitude.

What is the interference of light? The interference of light occurs when the source of waves is coherent, and the coherent sources should maintain the same frequency. The waves must have equal amplitude. The interference of light can be constructive interference or destructive interference.