Difference Between Interference and Diffraction

Difference Between Interference and Diffraction

Interference and diffraction are ideas that are closely connected, yet they are fundamentally separate kinds of waves that arise from different sources, despite their similarities. A wave will be formed when two waves with distinct origin points collide and their respective wavelengths merge to produce a single wave. An interference wave is a term used to describe this phenomenon.

The direction of a wave is affected when it comes into contact with an opening or obstruction, and the ensuing wave is referred to as a diffraction wave when it does so. It is vital to remember that interference waves are only actually produced when there are one or two wave sources present; when there are three or more wave sources present, the outcome is nearly invariably diffraction waves are produced.

Interference Vs. Diffraction

What makes a difference between Interference and Diffraction is the way their waves look. Interference happens when light waves merge as they travel through two separate beginning places at the same time. Diffraction, on the other hand, emerges as a result of the superposition of the subordinate wavelengths. The strength of the edge of interference is always the same, regardless of the situation. Diffraction, on the other hand, produces strange fringes.

What is the definition of Interference?

Interference happens when two waves originating from two separate places interact with one another and combine to produce a waveform that is completely different from the original.

It is called “in phase” two waves when the peaks and troughs of the waves are exactly aligned. The amplitudes of the two waves are simply put together to get the final waveform, which is called the sine wave.

It is known as constructive interference when the crests of two waves are combined together; the amplitude of the new waveform will equal the total of the respective amplitudes of the two original waves. When two waves are added together, it is known as destructive interference.

When waves are out of phase with one another and the crests and troughs overlap, they are referred to as “out of phase waves”.

If the waves are fully out of sync, i.e. one hundred and eighty degrees apart from each other, and the amplitudes of the peak and trough of opposing waves are identical, they will cancel each other out in a process known as destructive interference, which is a kind of electromagnetic interference.

Imagine yourself attempting to move a huge piece of furniture. This is what you’ll encounter.

It is constructive interference if two individuals push from the same end of the table since it will generate greater force than one person alone; but, if two people push from opposing ends of the table, the furniture will stay motionless, just as there is no wave amplitude with destructive interference.

In the context of light waves, it is also vital to understand that when projected onto a screen, an interference wave will have a constant and equal breadth between the bright and dark parts.

What is the definition of Diffraction?

Diffraction is a phenomenon in physics that occurs when waves bend around minor barriers, such as sound waves moving around a corner, or when waves spread out after passing through a narrow hole.

The secondary waveforms that occur from passing through or around the obstacle will be distinct from the initial waveforms, with possibly many different and varying phases and amplitudes as a consequence of the passage through or around the obstruction.

Since most wavelengths are very short, diffraction can only be seen at a substantial level when the gap size is equivalent to the wavelength. Because most wavelengths are extremely short, the narrower the gap, the more evident the diffraction.

Consider the image of waves of surf from the ocean crashing into a tight rocky passage to get a sense of what I mean. Now compare it to the impact of waves entering a harbor or a harbor entrance.

You will see that in the case of waves going through a small hole, the rounded waveform fanning out into the body of water on the other side of the aperture has a distinct shape from the flat waveform that first passed through.

As an example, consider a marina. Although greater amounts of water may be flowing from the ocean into the marina, the size of the aperture ensures that the water within the marina is only little affected by the ensuing diffraction waves. Similarly,

When particles move through slits or around an object, no diffraction waves are produced; instead, the particles continue on their original track, unaffected by the surrounding conditions.

Additionally, diffraction waves contain a range of distinct peak strengths, which is owing to the interaction of numerous and varying waveforms, in addition to the presence of several source points (greater than three), which is required in order to produce an induced diffraction wave.

We may notice an interference pattern on the opposite side of a diffraction wave if it travels through two unique gaps. This is because the two gaps function as two new source locations.

Difference Between Interference and Diffraction

  • Interference waves will result from the combination of two separate source points, while diffraction waves will result from the combination of three or more source points.
  • The intensities of the apices of interference wave apices are uniform and equal; on the other hand, the intensities of diffraction wave apices are diverse and uneven, owing to the fact that they are the sum of several separate waves.
  • Three, in an interference wave, the fringe width will also be equal, but with diffraction waves, the fringe width might be uneven.
  • Because of the many combining waves, the dip of an interference wave will always be equal to zero, but the trough of a diffraction wave might be any number of possibilities.
  • The original source or cause of the wave, for example, a rock thrown into a body of water, results in interference waves, but the secondary waves, which come from the primary passing through an opening or being struck by an item, are referred to as diffraction waves.


The most significant distinction between the two kinds of waves is in the manner in which they are both created. Diffraction waves are secondary waves that arise when a wave interacts with obstruction and are derived from the original wave source. Interference waves are derived from the original wave source.

The ability to see how interference and diffraction waves interact with one another provides us with a tool for better understanding the laws of our world, including in quantum physics with the double-slit experiment, which we will discuss later.

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