Electron Diffraction 1
Safety Warnings
Danger: High Voltage Hazard
Warning: Fragile Equipment
Purpose
Demonstrates the wave nature of electrons by showing diffraction rings from a polycrystalline graphite target. Students observe direct evidence for de Broglie's hypothesis and can verify \(\lambda = h/p\) quantitatively by varying the accelerating voltage.
Figure 1:
Electron diffraction pattern on the phosphorescent screen showing concentric rings from polycrystalline graphite. This image shows the clearest ring structure.
Figure 2:
Diffraction pattern at a different accelerating voltage, showing how ring spacing changes with electron wavelength.
Figure 3:
Beam positioned off-center on the phosphorescent screen, with faint diffraction rings visible around the central spot.
Figure 4:
Diffraction pattern at higher accelerating voltage, showing tighter rings consistent with shorter electron wavelength.
Figure 5:
Complete apparatus: power supply (left) with high voltage adjust, intensity, focus, and beam position controls; evacuated diffraction tube in acrylic housing (right). An analog voltmeter sits atop the power supply.
This apparatus operates at voltages up to 10 kV. Do NOT exceed 10 kV. Only trained lab staff should operate this equipment.
This is fragile equipment from the PHYS 2150 Introductory Modern Physics lab. The vacuum tube cannot be repaired if damaged. Handle with care and avoid mechanical shock.
Information: Equipment Status
This apparatus is currently out of service. Contact laboratory staff before planning to use it.