Mr Hassan’s Crookes’ Tube Laboratory
Cathode rays • fluorescence • magnetic deflection • the road to the electron
Reset
Pause
Pressure:
Medium
B-field:
OFF
Paddle:
ON
Particles:
ON
Ray path:
OFF
The
negative glow
(purple, near the cathode) is linked to
recombination
. The
positive column
(pink) is linked to
excitation
and
de‑excitation
.
Simulation controls
Gas pressure (inverse “vacuum”)
Medium
Higher pressure → more collisions → brighter discharge + more obvious striations (at the right range).
Accelerating voltage
6.0 kV
Higher voltage → electrons gain more kinetic energy → brighter fluorescence on the glass.
B-field: ON
Paddle wheel: ON
Magnetic field strength
0.0
Deflects cathode rays (direction via Fleming’s left-hand rule).
Particles: ON
Ray path: OFF
Striations: ON
Tip: if you want the “photo vibe”, try
Voltage ≈ 8–10 kV
and
Pressure ≈ 55–70
, with striations ON.
AQA steps
Student Q&A
Turning Points: Crookes tube
Step 1 of 6
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