A Haunting question on diffraction grating

In summary, the conversation discusses the effects of increasing the width of each slit while keeping the separation constant in a diffraction experiment. The answer states that the bright fringes will become brighter and there will be fewer fringes on the screen, but the individual is confused as to how this is possible, as they believed the fringes would become less bright due to decreased diffraction. They also inquire about the effects of increasing the separation of the slits on the number of fringes seen.
  • #1
mutineer123
93
0

Homework Statement


This question is pretty interesting, but a bit long, so bear with me

http://www.xtremepapers.com/CIE/International%20A%20And%20AS%20Level/9702%20-%20Physics/9702_w07_qp_2.pdf
question 5 part c

For (i) The width of each slit is increased but the separation remains constant.
Firstly what exactly does it mean to increase the width? Is d increasing? but it says separation remains constant
the answer says the bright fringes will become brighter and there will be fewer fringes on the screen. HOW?
I thought the fringes would become less bright, because increasing the slit mean diffraction decreases (considering the small wavelength of the light) so there should be less superposition, and hence the intensity of the resultant wave should be lower! ANd how in the world is "will be fewer fringes on the screen" derived??


And for the second one (ii) The separation of the slits is increased.
Why is increase in the nos. of maximas(more fringes seen) wrong?? following the equation dsin∅=nλ, if d increases then n will increase won't it??



Homework Equations





The Attempt at a Solution

 
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  • #2
mutineer123 said:

Homework Statement


This question is pretty interesting, but a bit long, so bear with me

http://www.xtremepapers.com/CIE/International%20A%20And%20AS%20Level/9702%20-%20Physics/9702_w07_qp_2.pdf
question 5 part c

For (i) The width of each slit is increased but the separation remains constant.
Firstly what exactly does it mean to increase the width? Is d increasing? but it says separation remains constant
the answer says the bright fringes will become brighter and there will be fewer fringes on the screen. HOW?
I thought the fringes would become less bright, because increasing the slit mean diffraction decreases (considering the small wavelength of the light) so there should be less superposition, and hence the intensity of the resultant wave should be lower! ANd how in the world is "will be fewer fringes on the screen" derived??


And for the second one (ii) The separation of the slits is increased.
Why is increase in the nos. of maximas(more fringes seen) wrong?? following the equation dsin∅=nλ, if d increases then n will increase won't it??



Homework Equations





The Attempt at a Solution



http://www.xtremepapers.com/CIE/International%20A%20And%20AS%20Level/9702%20-%20Physics/9702_w07_ms_2.pdf → answer sheet if anyone wants to view
 

1. What is a diffraction grating?

A diffraction grating is an optical device that is used to separate light into its component wavelengths. It consists of a large number of closely spaced parallel lines or grooves that act as a series of narrow slits, causing the light to diffract and produce a spectrum.

2. How does a diffraction grating work?

When light passes through a diffraction grating, it is diffracted or bent, causing each wavelength of light to be separated and form a distinct spectrum. This is due to the constructive and destructive interference of the light waves passing through the narrow slits of the grating.

3. What is the difference between a diffraction grating and a prism?

A diffraction grating separates light by diffraction, while a prism separates light by refraction. This means that a diffraction grating produces a more precise and accurate spectrum, while a prism produces a rainbow-like spectrum with overlapping colors.

4. What are the applications of a diffraction grating?

Diffraction gratings are commonly used in spectroscopy, where they are used to analyze the composition of light sources. They are also used in various scientific instruments, such as spectrometers and monochromators, and in laser technology.

5. How is the spacing of the lines on a diffraction grating determined?

The spacing of the lines on a diffraction grating is determined by the distance between the slits on the grating. This distance can be measured using a microscope or a diffraction grating ruler, or it can be calculated using the known properties of the grating.

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