Magnetic forces, magnetic fields, and Faraday's law

This course is a part of Physics, a 20-course Topic series from Khan Academy.

Magnetic fields are extremely useful. The magnetic field of the Earth shields us from harmful radiation from the Sun, magnetic fields allow us to diagnose medical problems using an MRI, and magnetic fields are a key component in generating electrical power in most power plants. In this topic you'll learn about the forces, fields, and laws that makes these and so many other applications possible.

This course contains 4 segments:

Magnets and Magnetic Force

In these videos and articles you'll learn how the magnitude of the magnetic force depends on the charge, velocity, and magnetic field. You'll also learn how to use the right hand rule to determine the direction of the magnetic force. Lastly, it will be explained how to determine the magnetic force on a current carrying wire.

Magnetic field created by a current

In these videos and articles you'll learn how the magnetic field created by a long straight wire depends on the current and distance from the wire. You'll also learn how to use the right hand rule to determine the direction of the magnetic field. The magnetic force between two current carrying wires will be discussed as well as the induced current in a wire moving through a magnetic field.

Electric motors

In these videos and articles you'll learn how electric motors rely on a magnetic force that can cause a torque which rotates a loop of wire. You'll also learn how commutators allow the direction the the current to switch, which causes the motor to continue turning.

Magnetic flux and Faraday's law

In these videos and articles you'll learn how magnetic flux depends on magnetic field strength, area, and angle. You'll also learn how Faraday's law states that a changing magnetic flux can cause an induced current. It will be shown how Lenz's law can allow you to find the direction of the induced current. Example problems will also be solved to show how to apply Faraday's law and Lenz's law.