# Possible to make 2 beams of light cancel?

• jasonhtml
In summary, the conversation discusses the possibility of using wave superposition to make two beams of light from different sources cancel each other out. While it is theoretically possible, it would be difficult to achieve and energy conservation must also be considered. The conversation also mentions looking for experiments that demonstrate this concept, but none are specifically known. Instead, the concept is explored through specific examples, showing why complete cancellation cannot occur in all locations.

#### jasonhtml

Last night, I was doing some really cool stuff with light interference, like the double split experiment and such. so, then i started wondering, is it possible to make 2 beams of light from different sources cancel each other out? [see attachment (gray are represents steam or something to make the beams visible)] i looked on the internet quite a bit and couldn't find anything :/

#### Attachments

• canceler.png
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Yes, you could theoretically make them cancel using wave superposition. But it would be very hard to do.

Probably, if they have exactly the same frequency, and you align them perfectly, it would be possible to cancel them in one direction. But I suppose you would have constructive interference in another direction (something with energy conservation).

ok, that's what i thought... but, does anyone know of any experiments that have been done that show this? (preferably on the internet so that i can look them up)

CompuChip is right, if the beams cancel in some place(s), they must constructively interfere somewhere else in order to conserve energy.

I never heard of experiments with light beams whose purpose was to confirm energy conservation. But we can look at specific examples, like the one depicted in Post #1, and show why we can't have cancellation everywhere.

Looking at the picture in Post #1, suppose there is a point within the beam-overlap where we have cancellation. That is, there is a 180 phase difference between the 2 beams at that point.

Now all you have to do is move 1/2 wavelength along one of the beams, so that the phase will change by 180 degrees for that beam. But for the other beam, you are moving across the beam and so there is no phase change for this second beam.

The net phase change is then 180 degrees. Coupled with the initial 180 degree phase difference, there is zero phase difference (i.e. complete constructive interference) in this 2nd location.

Regards,

Mark

## 1. Is it possible for two beams of light to cancel each other out?

Yes, it is possible for two beams of light to cancel each other out. This phenomenon is known as interference and occurs when two waves of light with the same wavelength and amplitude meet.

## 2. How does the process of light beam cancellation work?

Light beam cancellation occurs when two waves of light with the same wavelength and amplitude meet and their crests and troughs align, resulting in a cancellation of the wave amplitudes. This creates a region of darkness where the two beams intersect.

## 3. What factors can affect the ability of two beams of light to cancel each other out?

Some factors that can affect the ability of two beams of light to cancel each other out include the angle at which the beams intersect, the distance between the two beams, and the properties of the medium through which the light is traveling.

## 4. Can light beam cancellation occur in all types of light?

Yes, light beam cancellation can occur in all types of light, including visible light, infrared light, and ultraviolet light. It is a fundamental property of waves and occurs whenever two waves meet at the right conditions.

## 5. How is light beam cancellation useful in practical applications?

Light beam cancellation has many practical applications, such as in noise-cancelling headphones, optical filters, and interferometers used in scientific research. It can also be used to create patterns and images through the interference of multiple beams of light.