PhysicsMagnetic effects of electric currentClass 10Class 12

Electric motor & Fleming’s left-hand rule: interactive simulation

An electric motor converts electrical energy into mechanical energy. When a rectangular coil of insulated copper wire is placed in a magnetic field and current flows through it, opposite forces act on its two parallel arms.

Useful for: CBSE Boards, NEET, JEE Main

Try this

According to Fleming’s Left-Hand Rule, arm AB experiences a force in one direction while arm CD experiences an equal and opposite force. The split-ring commutator reverses the direction of current flow in the coil every half rotation, ensuring continuous unidirectional torque.

  1. 1

    Observe the green force arrows as the coil rotates.

    What you should see

    Arm AB has force pointing down/up, while arm CD has force in the exact opposite direction. This couple generates rotational torque.

  2. 2

    Toggle "Split-Ring Commutator" OFF.

    What you should see

    Without the split-ring commutator, current does not reverse; the coil overshoots, oscillates, and gets stuck at 90° where torque drops to zero!

  3. 3

    Increase Magnetic Field B to 2.0 T.

    What you should see

    Torque and force double instantaneously, demonstrating why powerful electromagnets are used in industrial motors.

Formulas behind it

Magnetic Force on Wire

F=I L Bsin⁡θF = I \, L \, B \sin\theta

Torque on Rectangular Coil

τ=N I A Bsin⁡θ\tau = N \, I \, A \, B \sin\theta

Current through Coil

I=VRI = \frac{V}{R}

Common mistakes

  • Confusing Fleming’s Left-Hand Rule with Right-Hand Rule. Left-Hand is for Motors (Force/Motion); Right-Hand is for Generators (Induced Current).
  • Thinking split rings are used in AC generators. Electric DC motors use split-ring commutators, whereas AC generators use continuous slip rings.
Stuck on a electric motor & fleming’s left-hand rule question?Snap it and get a whiteboard video solution.

FAQ

What is the function of the split-ring commutator in an electric motor?

The split ring acts as a commutator that reverses the direction of current in the coil every half-rotation (180°), ensuring the coil continues to rotate in the same direction.

What is the function of carbon brushes in an electric motor?

Carbon brushes maintain sliding electrical contact with the rotating split rings, supplying current from the external battery without tangling the connecting wires.

Related simulations

All 65 simulations
Lens ray diagramPhysics, Class 10 & Class 12Electric field linesPhysics, Class 12Circuit builderPhysics, Class 10 & Class 12Refraction and total internal reflectionPhysics, Class 10 & Class 12Human eye & defects of visionPhysics, Class 10 & Class 12Prism refraction, dispersion & rainbowPhysics, Class 10 & Class 12

Want a specific topic or simulation added?

Tell us in our feedback box which chapter or concept you want visualised next.

Send feedback