Electron Diffraction Experiment
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What is the primary objective of the electron diffraction experiment?

  • To investigate the diffraction of electrons from graphite crystals. (correct)
  • To study the deflection of light through a prism.
  • To analyze the resistance of different materials.
  • To measure the electric charge of electrons.

    • Which equipment is essential for the high-voltage supply in this experiment?

  • A high-value resistor of 1 MOhm.
  • A digital multimeter for voltage measurement.
  • A high-voltage supply unit capable of 0-10 kV. (correct)
  • A standard power supply of 120 V.

    • In terms of lab safety, which of the following protocols is most critical when using the high-voltage equipment?

  • Ensuring all connections are insulated and secure. (correct)
  • Having a water source nearby for fire safety.
  • Wearing cotton gloves.
  • Using wooden tools to handle equipment.

    • When interpreting results from the electron diffraction experiment, what is the primary measurement derived from the data?

    <p>The interplanar spacing of graphite.</p> Signup and view all the answers

    Which of the following data analysis techniques is most appropriate for analyzing the diffraction patterns obtained?

    <p>Fourier analysis to extract frequency components.</p> Signup and view all the answers

    What method is used to determine the average radius of the diffraction pattern?

    <p>Measure both the inner and outer circles and average their sums</p> Signup and view all the answers

    During the equipment shutdown process, which step should be performed first?

    <p>Reduce the High value resistor to zero before other actions</p> Signup and view all the answers

    Which statement best describes the importance of measuring both inner and outer circles in this experiment?

    <p>It provides a more accurate evaluation of the wave interference patterns</p> Signup and view all the answers

    In the scientific reporting of an experiment, how is the radius of the diffraction pattern typically expressed?

    <p>As the average of the inner and outer circle measurements</p> Signup and view all the answers

    What is the primary goal of the procedure involving the adjustment of the HV-power supply and the High value resistor during operation?

    <p>To regulate the energy input affecting the experiment outcomes</p> Signup and view all the answers

    What is the purpose of adjusting the High value resistor during the experiment?

    <p>To keep the voltage constant throughout the experiment</p> Signup and view all the answers

    When recording the radius of electron diffraction, which factors could potentially affect the measurements?

    <p>Voltage stability and precision of measurement tools</p> Signup and view all the answers

    What does the calculation of the electron wavelength using de Broglie's equation depend on?

    <p>The potential difference applied and the mass of the electron</p> Signup and view all the answers

    Which step is crucial to ensure reproducibility in the experimental results?

    <p>Measuring the radius at distinct voltage intervals</p> Signup and view all the answers

    What could a steeper slope in the graph of radius versus wavelength indicate?

    <p>A smaller interplanar spacing in the material</p> Signup and view all the answers

    Why is it important to repeat the experiment with varying voltage from high to low?

    <p>To identify any anomalous data or inconsistencies</p> Signup and view all the answers

    What does the variable 'd' represent in the interplanar spacing formula?

    <p>The separation distance between crystal planes</p> Signup and view all the answers

    In order to effectively analyze the data collected, what is a recommended approach to graphing the results?

    <p>Plotting radius against voltage to establish trends</p> Signup and view all the answers

    Which precaution should be prioritized to ensure lab safety during the experiment?

    <p>Ensuring the HV-power supply is connected to a surge protector</p> Signup and view all the answers

    What is a likely outcome of incorrectly calculating the radius of electron diffraction?

    <p>It would lead to inaccurate calculations of interplanar spacing</p> Signup and view all the answers

    What is the correct alignment of the Helmholtz coil to ensure uniform magnetic field strength?

    <p>Coils should be oriented with centers aligned and spaced correctly.</p> Signup and view all the answers

    In the narrow beam tube setup, what is the purpose of the D.C. power supply?

    <p>To facilitate current flow by creating a potential difference.</p> Signup and view all the answers

    Which adjustment should be made to prevent damage to the cathode during tube operation?

    <p>Set the grid voltage and anode voltage to their zero positions before starting.</p> Signup and view all the answers

    What must be considered when calculating the energy levels of electrons in the narrow beam tube?

    <p>Both anode and grid voltages contribute to the total energy of electrons.</p> Signup and view all the answers

    During the operation of the narrow beam tube, which voltage levels need to be carefully monitored?

    <p>Grid voltage (-50 V to 0 V) and Anode voltage (0 V to 250 V).</p> Signup and view all the answers

    What is the fixed filament voltage used to heat the filament in a narrow beam tube?

    <p>6.3 V</p> Signup and view all the answers

    Which voltage range can be adjusted for the grid voltage in a narrow beam tube?

    <p>-50....0 V</p> Signup and view all the answers

    How is the energy and speed of electrons in the narrow beam tube determined?

    <p>From the anode voltage applied</p> Signup and view all the answers

    What is the maximum anode voltage available for adjustment in the narrow beam tube setup?

    <p>250 V</p> Signup and view all the answers

    What is the purpose of adjusting the grid voltage in a narrow beam tube?

    <p>To control the number of electrons emitted</p> Signup and view all the answers

    In terms of voltage measurement, what instrument is used to measure the voltage difference between the cathode and anode?

    <p>A voltmeter V</p> Signup and view all the answers

    When adjusting the narrow beam tube, which condition best represents the anode voltage regulation?

    <p>It can be adjusted from 0 to 250 V.</p> Signup and view all the answers

    What general effect does increasing the anode voltage have on the electrons in the narrow beam tube?

    <p>Increases their potential energy.</p> Signup and view all the answers

    Which adjustment is critical when ensuring that the electron beam maintains a radius of 5 centimeters?

    <p>Matching the current from the Helmholtz coil with the anode voltage</p> Signup and view all the answers

    What is the result of increasing the anode voltage while keeping the current through the Helmholtz coil constant?

    <p>Radius of the electron trajectory might initially increase</p> Signup and view all the answers

    What effect does reversing the magnetic field direction in the Helmholtz coil have on the electron beam?

    <p>The direction of the electron trajectory will reverse</p> Signup and view all the answers

    In the process of adjusting the current in the Helmholtz coil, what optimal limit should not be exceeded?

    <p>5 amperes</p> Signup and view all the answers

    For measurements at varying radii of 4, 3, and 2 cm, what procedure must be followed?

    <p>Maintain a constant voltage while varying the current</p> Signup and view all the answers

    Which of the following methods is used to record the results of the electron trajectories in the experiment?

    <p>Visualizing the electron beam on a photographic medium</p> Signup and view all the answers

    What should the trajectory of the electrons resemble when the circuit is correctly configured?

    <p>A closed circular path without any deviations</p> Signup and view all the answers

    Which aspect of the experiment involves manipulating the physical orientation of the narrow beam tube?

    <p>To rotate it during the measurement of electron trajectories</p> Signup and view all the answers

    Study Notes

    Electron Diffraction Experiment

    • Objective: To study electron diffraction from graphite crystals and determine the interplanar spacing of graphite.

    Equipment

    • Electron diffraction tube assembly
    • High-voltage supply unit (0-10 kV)
    • High-value resistor (10 MOhm)
    • Power Supply (0-600 VDC)
    • Vernier caliper (plastic)
    • Connecting cords (various lengths and colors, including red, blue, yellow, black, 50, 250, and 750 mm)

    Theory

    • De Broglie Hypothesis: Matter particles, such as electrons, protons, and neutrons, exhibit wave-like properties. The wavelength (λ) associated with a particle is inversely proportional to its momentum (p): λ = h/p, where h is Planck's constant.
    • Electron Wavelength Calculation: The wavelength of an electron accelerated through a potential difference (U) is given by: λ = h / √(2meU), where m is the electron mass and e is the electron charge.
    • Bragg's Law: When electrons are diffracted by a crystal lattice, constructive interference occurs when the path difference between waves scattered from different planes is an integer multiple of the wavelength. This is expressed by Bragg's Law: 2d sin θ = nλ, where d is the interplanar spacing, θ is the Bragg angle, and n is an integer.
    • Graphite Crystal Structure: Graphite consists of layers of carbon atoms arranged in a hexagonal lattice. The interplanar spacing (d) within the layers is a key property for diffraction analysis.

    Procedure

    • Setup: Assemble the equipment according to a diagram (figure 3).

    • High Voltage Adjustment: Set the high-voltage power supply to 3 kV, and adjust the high-value resistor according to the instrument's specifications.

    • Electron Diffraction Measurement: Vary the accelerating voltage from 3 kV to 7.5 kV in steps of 0.5 kV. Measure the radii (r) of the diffracted electron rings for each voltage. Repeat measurements for decreasing voltages (7.5 to 3 kV).

    • Data Recording: Record all measurements of radii for each voltage.

    • Graphing: Plot radius (r) versus wavelength (λ) to obtain a graph. The slope of this graph (A) represents a value related to the interplanar distance and can be used to calculate that parameter.

    • Calculating Interplanar Spacing (d): Using the slope from the graph and the equation (2R/A), determine the interplanar spacing (d) from the experiment's equipment and setup (Where R represents the radius of the circular screen).

    • Analysis and Conclusion: Analyze the results, discuss observations, and explain any discrepancies. Address the question of whether the graphite used is single-crystalline or polycrystalline.

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    Related Documents

    Lab 3 Electron Diffraction PDF
    Lab 4: Measurement e/m of Electron PDF

    Description

    This quiz covers the principles and equipment used in the electron diffraction experiment aimed at exploring the interplanar spacing of graphite crystals. Key theories such as the De Broglie hypothesis and Bragg's Law will also be assessed, emphasizing the wave-particle duality of matter. Prepare to test your understanding of the concepts and calculations involved in this detailed experiment.

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