Chemistry Sim · Atomic Models

Thomson's CRT Experiment

Fire cathode rays through electric and magnetic fields. Watch the beam bend and prove electrons exist inside atoms — disproving Dalton's indivisible sphere.

Cathode Ray Tube

Adjust voltage and magnetic field. Observe how the beam bends toward the positive plate.

Cathode (−) Anode (+) + Plate − Plate Screen High Voltage Supply
Top +0 VBottom +
Off80%Max
🧲 Magnetic Field: (Thomson used both E and B fields)

📊 Live Observations

Beam Deflection
0 mm
Charge Detected
NEGATIVE

What Thomson Proved

The evidence that destroyed Dalton's indivisible atom.

❌ What Dalton Claimed

Atoms are indivisible, solid spheres — the smallest unit of matter. No subatomic particles exist.

✅ What Thomson Proved

Cathode rays are streams of negatively charged particles (electrons) — atoms ARE divisible!

🎯 Key Evidence That Disproved Dalton

  • Deflection toward positive plate → proves cathode rays carry negative charge
  • Same deflection regardless of cathode material → electrons exist in ALL atoms
  • Mass/charge ratio measured → particles are ~1/1836 mass of hydrogen atom
  • Conclusion: Atoms contain smaller subatomic parts → Dalton's model is wrong!