Electricity & Magnetism

A quick review of what we’ve learned… through videos!

Relating Electricity & Magnetism Watch this video. Create some hypotheses to explain what you saw.

Relating Electricity & Magnetism Under what conditions did the wire jump? Are stationary electric charges affected by magnetic fields? What about moving electric charges?

Relating Electricity & Magnetism How can we explain this behavior thinking about magnetic fields? Pg. 563, Figure 2

Motor Principle A current-carrying conductor crossing an external magnetic field, experiences a force perpendicular to the magnetic field and the direction of the current. Current flows from positive to negative

Motor Principle Right Hand Rule #3 Thumb in direction of conventional current Fingers in direction of magnetic field Palm facing direction of force Current flows from positive to negative

Practice Determine the direction of the force on the conductor:

Motor Parts of a Motor Cell – Provides current Field magnet – Provides external magnetic field Coil - Part of the motor that rotates (armature) Commutator – “Split ring” that rotates with the coil Brushes – Connects commutator and cell

Motor Principle For a motor to turn continuously, the current must change direction in the loop. In a DC or direct-current motor, this is accomplished with brushes & the split-ring commutator

Parts of a Motor Name the parts of the motor that are labelled in the diagrams below!

Motor Principle

Motor Principle

Motor

Motor Principle

Motor

Motor

Motor

Homework Pg. 566 #1, 2 Pg. 571 #1, 2