Diffraction, Gratings and Resolving Power

Name: Diffraction, Gratings and Resolving Power
Author: StemPy Lab

Light bends round a narrow slit and spreads. We study the single slit and the width of its central maximum, then the double slit and the grating with diffraction included. The Rayleigh limit decides what a telescope, a microscope or an eye can tell apart. It serves the Indian syllabus (NCERT, JEE Main) and the matching topic of A-Level, IB and AP.

3 lessons, about 1 h 50 min3 simulations10 problems7 practice questionsPython in every lesson

Created by StemPy Lab

Course outline (3 lessons)

Lesson 1about 35 min
Diffraction at a single slit
Light spreads out when it passes through a slit about as narrow as its wavelength. The pattern of a single slit has a wide central maximum and weak maxima on both sides, with dark places at $a\sin\theta = n\lambda$ . The central maximum is $2\lambda D/a$ wide, so a narrower slit gives a wider pattern.
1 simulation2 practice questions1 Python program3 problems1 Python lab
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Lesson 2about 40 min
The double slit with diffraction and the grating
A real double slit shows fringes inside the single-slit pattern of each slit, and some orders are missing. A diffraction grating has a great number of slits. It gives sharp bright lines at $d\sin\theta = m\lambda$ and a spectrum of each order for white light.
1 simulation2 practice questions2 Python programs4 problems1 Python lab
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Lesson 3about 35 min
Resolving power and the Rayleigh limit
A star seen through a telescope is not a point but a small disc with rings, because of diffraction at the round aperture. Two stars can be told apart only if their angle is at least $1.22\lambda/D$ , the Rayleigh limit. A bigger aperture and a shorter wavelength resolve more detail.
1 simulation3 practice questions1 Python program3 problems1 question set1 note
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Diffraction and Gratings: Timed Test

10 questions · 25 min

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Diffraction, Gratings and Resolving Power

Course outline (3 lessons)

Diffraction at a single slit

The double slit with diffraction and the grating

Resolving power and the Rayleigh limit

Test Your Learning

Your teacher

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