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What was the primary objective of the electron diffraction experiment?
Who first suggested that matter might have wave-like properties?
What was a significant outcome of Davisson and Germer's experiment?
In the context of electron diffraction, what does the distance 'd' represent?
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What is the interference pattern in electron diffraction analogous to?
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What discovery did Davisson and Germer make regarding electron behavior?
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What constant is used to determine the wavelength of matter according to de Broglie’s hypothesis?
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What effect did Clinton Davisson and Lester Germer discover in their experiment?
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What is the main purpose of the electron gun in this experiment?
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What feature of the carbon target causes the appearance of the interference pattern?
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How do you calculate the angle φ in the experiment?
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What is the minimum anode voltage required to see the rings?
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What should be done after switching on the heater in the experiment?
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Which of the following describes the structure of the carbon used in the experiment?
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What is the purpose of measuring the diffraction angle θ?
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What happens to the rings as the accelerating voltage is adjusted?
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What represents the de Broglie wavelength for an electron?
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How is the momentum of electrons calculated as they leave the electron gun?
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What is the condition for constructive interference in wave diffraction?
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According to Bragg’s Law, what is the relationship between the wavelength, distance, and angle of diffraction?
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What is the formula for calculating the intra-atomic distance in a crystal?
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In the formula $d = rac{h}{2 ext{sin}( heta) ext{sqrt}(2emeVa)}$, what do the variables represent?
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Which of the following safety measures is essential when working with high voltage in the electron diffraction experiment?
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Which piece of equipment is NOT required for the electron diffraction experiment?
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What does the equation $L \sin 2\theta = R \sin \phi$ relate to in an experimental setup?
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What is the significance of the distance L in the diffraction condition?
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Which equation involves the electron's velocity in relation to diffraction?
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What is the main advantage of using electrons instead of light in microscopy?
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What is the accepted value for the distance between the outer atomic layers in graphite?
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In what context is a scanning electron microscope (SEM) similar to an optical microscope?
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In the study of diffraction, how should $1/V_a$ be plotted in relation to $sin \theta$?
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Which measurement needs to be compared against accepted values to validate distances in the experiment?
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Study Notes
Electron Diffraction Experiment
- Objective: Observe diffraction of electrons on a graphite target and calculate interatomic spacing in graphite.
Theoretical Background
- Wave-particle duality: Matter exhibits wave-like properties, as proposed by Louis de Broglie.
- De Broglie wavelength: λ = h/p, where h is Planck's constant and p is momentum.
- Electron diffraction: Electrons diffract from crystal planes, similar to light diffraction from a grating.
- Bragg's Law: nλ = 2d sin θ, where n is an integer, λ is electron wavelength, d is interatomic spacing, and θ is diffraction angle.
- Interatomic spacing calculation: d = λ / (2 sin θ).
Experimental Setup and Procedure
- Electron gun: Heats a cathode to emit electrons and accelerates them with an anode voltage (Va).
- Graphite target: Electrons diffract from the graphitized carbon target.
- Diffraction pattern: Circular rings on a phosphorus screen indicate constructive interference.
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Measurement procedure:
- Measure diffraction angle θ with masking tape and a ruler.
- Determine the arc length (s) of the diffraction rings.
- Calculate θ using formula: L sin 2θ = R sin φ, where L is target-screen distance, R is screen curvature radius, and φ is the angle between incident beam and diffracted beam.
Data Analysis
- Plot 1/Va versus sin θ for inner and outer rings.
- Calculate slope for each line.
- Determine interatomic spacing d10 (inner ring) and d11 (outer ring) from the slope.
Results
- Expected values for d10 and d11: 0.213 nm and 0.123 nm, respectively.
Applications
- Electron diffraction is a powerful tool for studying materials at atomic scale.
Limitations of Optical Microscopy
- Diffraction limit: Resolution limited by the wavelength of light (≈ 400 nm).
Scanning Electron Microscope (SEM)
- Uses electrons as "light" source to overcome the diffraction limit and achieve higher resolution.
- Magnetic lenses instead of glass lenses.
- Achieves angstrom-scale resolution allowing observations of very small features.
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Description
This quiz explores the fundamentals of electron diffraction, focusing on the theoretical background including wave-particle duality and Bragg's Law. You will learn how to calculate interatomic spacing in graphite using experimental observations. Test your knowledge on electron behavior and experimental processes related to diffraction.
