Define a diffraction grating .

An optical component consisting of a large number of thin, equally spaced, parallel slits that diffracts monochromatic light into bright and dark fringes.

State two ways to reduce the percentage uncertainty in h when determining wavelength with a diffraction grating.

Take multiple measurements of h (three to eight) and average Use a Vernier scale to measure h Measure across all the fringes and divide by the number of fringes Use a grating with more lines per mm, so h is larger

True or False? Increasing the grating-to-screen distance D improves the experiment with no drawbacks.

False. Increasing D increases the fringe separation, but it may also decrease the intensity of light reaching the screen.

A LevelPhysicsCambridge (CIE)Flashcards8. SuperpositionThe Diffraction Grating

The Diffraction Grating (Cambridge (CIE) A Level Physics): Flashcards

Exam code: 9702

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FrontThe Diffraction Grating
Define a diffraction grating.
FrontThe Diffraction Grating
State the diffraction grating equation, defining each symbol.
BackThe Diffraction Grating
$d \sin (θ) = n λ$
d = spacing between adjacent slits (m)
θ = angle to the order of maxima (degrees)
n = order of maxima (n = 0, 1, 2, 3...)
λ = wavelength of light source (m)

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Cards in this collection (8)

Define a diffraction grating.
An optical component consisting of a large number of thin, equally spaced, parallel slits that diffracts monochromatic light into bright and dark fringes.
State the diffraction grating equation, defining each symbol.
$d \sin (θ) = n λ$
- d = spacing between adjacent slits (m)
- θ = angle to the order of maxima (degrees)
- n = order of maxima (n = 0, 1, 2, 3...)
- λ = wavelength of light source (m)
How is the slit spacing d calculated from the number of lines per unit length, N?
$d = \frac{1}{N}$
How is the highest order of maxima, n, visible from a diffraction grating calculated?
$n = \frac{d}{λ}$
(found by setting θ = 90°, since sin θ = 1). If the result is not a whole number, round down to find the highest order visible.
The highest visible order of maxima occurs when the diffraction angle θ = ..........°, since sin θ = 1.
90
In the experiment to determine the wavelength of light using a diffraction grating, how is the angle θ to a given order of maxima found from the measured distances h and D?
$\tan (θ) = \frac{h}{D} \Rightarrow θ = \tan^{- 1} (\frac{h}{D})$
where h = distance from the centre to the order of maxima on the screen, and D = distance from the grating to the screen.
State two ways to reduce the percentage uncertainty in h when determining wavelength with a diffraction grating.
- Take multiple measurements of h (three to eight) and average
- Use a Vernier scale to measure h
- Measure across all the fringes and divide by the number of fringes
- Use a grating with more lines per mm, so h is larger
True or False?
Increasing the grating-to-screen distance D improves the experiment with no drawbacks.
False.
Increasing D increases the fringe separation, but it may also decrease the intensity of light reaching the screen.

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