# Physics lessons

Here you will find 52 detailed lessons about physics at different levels of difficulty.
Lesson
Level 3 (with higher mathematics)

## Differential Equations (DEQ): All the Basics Everyone Should Know

Learn what differential equations are, what types there are (ordinary, partial, linear, homogeneous), and what boundary and initial conditions are good for.

Lesson
Level 1 (suitable for all)

## Electric Current: The Most Basic Explanation From a Physics Point of View

In this lesson you will learn the basics of the electric current, i.e. the definition, its physical meaning and unit.

Lesson
Level 2 (without higher mathematics)

## Physical Quantities and Their Units

List of important physical quantities, their symbols, (derived) units and examples with images.

Lesson
Level 2 (without higher mathematics)

## Photon Energy - The Energy of Light Particles

Here you will learn how to determine energy of photons and how this energy depends on the color of light (frequency or wavelength).

Lesson
Level 2 (without higher mathematics)

## Simple (Series and Parallel) Circuits. The Basics.

Here you will learn how an electrical circuit works and how to apply Ohm's Law to it. You will also learn about parallel and series circuits and their difference.

Lesson
Level 1 (suitable for all)

## The 16 most Important Geometric Objects: Overview with Formulas and Properties

Illustrated overview of all geometric solids with important properties as well as formulas for areas, volumes and other quantities.

Lesson
Level 2 (without higher mathematics)

## Photoelectric effect: How to understand the revolutionary experiment just like Einstein did

Here you will learn how the photoelectric effect is explained quantum mechanically, how the stopping voltage method works and everything else you need to know.

Lesson
Level 2 (without higher mathematics)

## The 12 Important Physical Constants

Learn about important physical constants and what their formula symbols and SI units are.