Skip to main content

Want to understand physics?

I am Alexander Fufaev, physicist and owner of this website. Here you can find free, high-quality content about physics. Courses, exercises with solutions, questions and answers and much more!
Physics courses


A course is an ordered learning unit that will take you step by step through a comprehensive physics topic so that by the end you will have mastered it.

View courses

Neue Inhalte

Level 2 (suitable for students)

Lorentz force simply explained in 6 minutes!

In this video you will learn how to determine the direction of the Lorentz force using left/right hand rule and how this force is calculated and related to the centripetal force.

Content of the video
  1. 00:00 What is Lorentz force?
  2. 00:28 Moving charge perpendicular to the magnetic field
  3. 01:12 Determine Lorentz force direction
  4. 02:40 Lorentz force qvB-equation
  5. 04:12 Movement at an angle to the magnetic field
  6. 04:59 Lorentz and centripetal force
  7. 06:20 Determine velocity of the electron
Level 3 (for advanced students)

Inductive reactance of a coil briefly explained

Learn what inductive reactance is and how to determine it for a coil (inductor) in an AC circuit.

Content of the video
  1. 00:00 What is inductive reactance?
  2. 00:30 Calculate inductive reactance
  3. 01:32 Example
  4. 01:53 RMS current through the coil