✕Wrong mental model
An electron is NOT a little ball rotating around its own axis like Earth.
QUANTUM PHYSICS · CLASSES 11–12
Electron spin.
Not what you think.
The electron is not a microscopic spinning planet. Explore the quantum state, make real predictions, send silver atoms through a virtual magnet and discover why each spin measurement has only two outcomes.
SIX LIVE EXPERIMENTSQUANTITATIVE + 3D-STYLEFREE · NO ACCOUNT
START WITH THE RIGHT PICTURE
The visual model: misconception → quantum reality
✓What quantum spin actually is
Spin is an intrinsic quantum property associated with angular momentum and magnetic moment. The arrow on a Bloch sphere represents a quantum state—not a physical rotation or electron trajectory.
ANY CHOSEN MEASUREMENT AXIS
Two outcomes. Many possible states.
Sₙ = +ℏ/2Spin + along the axis
Sₙ = −ℏ/2Spin − along the axis
Important: ±ℏ/2 are measurement projections. A qubit can be in infinitely many superposition states, and measuring another axis can change the probabilities.
EXPERIMENTAL EVIDENCE · 1922
Stern–Gerlach: two silver-atom beams
The original experiment used neutral silver atoms with one unpaired electron—not a beam of free electrons. Their two deflections reveal quantized spin projection.
Electron spin contributes to magnetic ordering.
Pauli exclusion limits one spatial orbital to two opposite spins.
Spin-½ states can encode a qubit and be controlled by quantum gates.
Clinical MRI primarily measures nuclear spin (mostly hydrogen protons), not electron spin.
THE CORRECT MENTAL MODEL
Spin is not spinning
A quantum state is not a tiny rotating ball.
QUANTUM STATE SPACE · NOT AN ELECTRON ORBIT
PREDICTED QUANTUM OUTCOMES
Probability, not a pre-spinning arrow
WHAT THE EQUATIONS MEAN
Sₙ = ±ℏ/2
YOUR QUANTUM NOTEBOOK
Save evidence, not just guesses.
Which measurement axis changed the result? Why did selecting +X alter a later Z measurement? Record a short observation—saved only on your device.
TEACHER'S NOTE · CLASS 11–12
What this lab proves—and what it does not
Spin-½ is an intrinsic degree of freedom. The outcomes of measuring a spin component along any chosen axis are +ℏ/2 and −ℏ/2; the magnitude of angular momentum is √3ℏ/2, not ℏ/2. Bloch arrows encode pure quantum states, not classical rotation or known hidden spin directions. The historical Stern–Gerlach beam consisted of neutral silver atoms. Ordinary clinical MRI mainly detects nuclear spin (hydrogen protons). This simulation is an educational extension connecting atomic structure, magnetism and introductory quantum information—not an official board practical or real MRI instrument.