13022022 Forces on Charged Particles and Magnetic Fields

13/02/2022 Forces on Charged Particles and Magnetic Fields (Summary Notes pages 14 and 15) Particles and Waves M Ashton 2013

What are we learning today? �What happens to charges in a magnetic field.

Magnetic Field Around a Current Carrying Wire �Activity: FCP L 3 – Moving Charged Particles Produce a Magnetic Field �The compasses move indicating that a magnetic field is present when the supply is switched on.

�The direction of the magnetic field depends on the direction of the electron current flow. �The direction can be determined using the left hand grip rule. Current going up Current going down

Demonstration �This will allow you to determine what happens to a current carrying wire in a magnetic field. • A wire carrying an electric current will experience a force when placed in a magnetic field. • Why?

�A moving electric charge creates its own magnetic field. �This means it will experience a force if it moves through a magnetic field. Click for Cloud Chamber Simulation

Electron Current Motor Rule �One common method is known as the right-hand motor rule. This is shown on the right. F �The thumb gives the motion (M), the first finger gives the field (F) and the second finger is the direction of electron current (I). M I

Conventional Current Motor Rule �For a conventional current, the direction of movement is opposite to the direction for a negative charge.

Example �In which direction will the force act? Movement (current) Left hand rule +

Example �In which direction is the force acting? Right hand rule Movement (current)

Example �In which direction is the force acting? Left hand rule +

Example �In which direction is the force acting? Right hand rule -

Now complete Qs 34 -39 on pages 12 & 13.