3D lab · Moving charges

Charged Particle in E and B Fields (Helix, Cycloid) 3D

Launch electrons, protons and alpha particles into magnetic and electric fields in 3D and see circles, helices and cycloids with their radius, pitch and period.

Last updated: 26 October 2026

Direct answer

Launch electrons, protons and alpha particles into magnetic and electric fields in 3D and see circles, helices and cycloids with their radius, pitch and period.

The magnetic force is always perpendicular to the velocity, so it bends the path without changing the speed. Add an electric field to get a drift or a stretching helix.

Simulation

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Charged Particle in E and B Fields (Helix, Cycloid) 3D

Moving charges

Fields B only (helix)

Particle Proton

Speed (×10⁵ m/s) 5

Angle between v and B (°) 60°

B (mT) 20 mT

E (kV/m) 10 kV/m

Drag to rotate, two fingers or right-drag to pan, scroll or pinch to zoom. The toolbar has views, cutaway, measure and “show the maths”.

What's happening? The magnetic force is always perpendicular to the velocity, so it bends the path without changing the speed. Add an electric field to get a drift or a stretching helix.

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Where it is in NCERT: Class 12 Physics Part I, “Moving Charges and Magnetism” (Magnetic force on a current-carrying conductor, Motion in a magnetic field, Ampere's circuital law, The solenoid and the toroid); Class 12 Physics Part I, “Magnetism and Matter” (The bar magnet, Magnetism and Gauss's law, Magnetisation and magnetic intensity, Magnetic properties of materials) · ncert.nic.in
Topic notes and formulas: Magnetic Effects of Current and Magnetism
Printable formula sheet
Chapter-wise JEE Main PYQs (14)

Watch and try

The matching part of a free lecture: Motion of a charged particle in magnetic & electric field (4:01:34) — JEE Wallah
See it in 3D: Magnetic Field Around a Straight Wire (3D) · Magnetic Field of a Current Loop and Solenoid (3D)
Other trusted simulations: Magnets and Electromagnets (PhET, University of Colorado) · 3-D Magnetostatic Field Simulation (Paul Falstad)

Terms used on this page

Electric field (E)Pitch (of a helix)

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FAQs

Frequently asked questions

Why does a charge move in a helix in a magnetic field?

The velocity component along B is unchanged while the perpendicular component goes round in a circle.

Does the period depend on speed?

No. T = 2πm/(qB) for non-relativistic speeds; this is why a cyclotron works.

Charged Particle in E and B Fields (Helix, Cycloid) 3D

Launch electrons, protons and alpha particles into magnetic and electric fields in 3D and see circles, helices and cycloids with their radius, pitch and period.

Try it

Charged Particle in E and B Fields (Helix, Cycloid) 3D

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