# NEET Physics Wave Optics : Multiple Choice Previous Years Questions MCQs 4 | Summary and Q&A

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October 4, 2017
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NEET Physics Wave Optics : Multiple Choice Previous Years Questions MCQs 4

## TL;DR

Diffraction of light occurs when the size of the obstacle or aperture is comparable to the wavelength of visible light.

## Key Insights

• π Diffraction of light occurs when the size of the obstacle or aperture is comparable to the wavelength of visible light.
• π¨π« The width of the central maxima in a diffraction setup is inversely proportional to the width of the slit.
• π To observe diffraction, the value of the aperture size should be comparable to the wavelength of light.
• π The energy flux of light falling on a perfectly reflecting surface can be used to calculate the average force exerted on the surface.
• π Force is equal to the change in momentum, which can be calculated by subtracting the momentum of the reflected light from the incident light.
• π The momentum of light is related to its energy through the equation energy = momentum x speed of light.
• βΊοΈ The distance between forced dark fringes on either side of the central bright fringe can be calculated using the formula Y = lambda / (a x D).

## Transcript

hello friends this video unmeet wave optics is brought to you by Rancher comm no more fear from exam question number 14 Gershon to observe diffraction of light the size of obstacle approaches should be of the order of 10 to the power minus 7 meters reason 10 to the power minus 7 meters is the order of wavelength of visible light now many Lang's you... Read More

### Q: What should be the size of the obstacle or aperture to observe diffraction of light?

The size of the obstacle or aperture should be approximately equal to the wavelength of visible light.

### Q: How does the width of the slit affect the width of the central maxima?

The width of the central maxima is inversely proportional to the width of the slit. A larger slit width results in a smaller central maxima.

### Q: Why should the value of the aperture size be comparable to the wavelength of light for diffraction to occur?

Diffraction can be observed when the value of the aperture size is similar to the wavelength of light. If the aperture size is significantly larger or smaller, diffraction will be limited or nonexistent.

### Q: How can the distance between forced dark fringes on either side of the central bright fringe be calculated?

The distance can be calculated using the formula Y = lambda / (a x D), where Y is the distance, lambda is the wavelength of light, a is the width of the slit, and D is the distance between the slit and screen.

## Summary & Key Takeaways

• Diffraction of light occurs when the size of the obstacle or aperture is approximately equal to the wavelength of visible light.

• The width of the central maxima in a diffraction setup is inversely proportional to the width of the slit.

• To observe diffraction, the value of the aperture size should be comparable to the wavelength of light.