OCR A-Level Physics B H557
Planning
Implementing
Analysis
Evaluation
Practical Skills
Use of Apparatus and Techniques
Fundamental Data Analysis
Imaging and Signalling
Sensing
Mechanical Properties of Materials
Waves and Quantum Behaviour
Space, Time and Motion
Creating Models
Out Into Space
Our Place in the Universe
Matter: Very Simple
Matter: Hot or Cold
Electromagnetism
Charge and Field
Probing Deep Into Matter
Ionising Radiation and Risk
Waves and Quantum Behaviour
Diffraction at a narrow aperture
- 3 things to know
- Components 01, 02 and 03
Overview
Recall questions on when spreading at a gap is greatest, water waves through wide and narrow gaps, the single-slit pattern, angular spread, and why apertures limit a telescope or camera.
What you need to know
Answer each one before you reveal it.
Under what condition is diffraction at an aperture most pronounced?
Describe the pattern produced when laser light passes through a single narrow slit onto a screen.
Questions from this subtopic
Each one with the model answer underneath.
- 1
Define diffraction.
Model answer
Diffraction is the spreading out of a wave as it passes through an aperture or round the edge of an obstacle.
- 2
Under what condition is diffraction at an aperture most pronounced?
Model answer
Diffraction is greatest when the width of the aperture is comparable with the wavelength.
- 3
What happens to a plane water wave passing through a gap much wider than its wavelength?
Model answer
It carries on with almost straight wavefronts, spreading noticeably only near the edges of the gap.
- 4
What happens to a plane water wave passing through a gap about one wavelength wide?
Model answer
It emerges as almost circular wavefronts that spread into the whole region beyond the gap.
- 5
Describe the pattern produced when laser light passes through a single narrow slit onto a screen.
Model answer
A broad bright central band appears, with much fainter bands on either side separated by dark minima.
- 6
How does the width of the central diffraction maximum change as the slit is narrowed?
Model answer
The central maximum becomes wider, because narrowing the slit increases the angular spread of the light.
Other ways to work this
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