 B-060A-435D-A884-5EE93A1636A B-060A-435D-A884-5EE93A1636A3  Electricity’s Power, Part One

Topic 6 – Generators and Motors Science 9 - Electricity

Would you use a bunch of batteries to light a sports field?  Why not?  Batteries are fine for portable power, but they cannot supply the quantities of electricity required for outdoor lighting, heavy appliances, and large industrial machinery.

 Most of our energy comes from the conversion of mechanical energy.  Mechanical Energy: associated with moving parts  Ex: windmill, spinning turbines, moving water

Electricity to Magnetism  Hans Christian Oerstad & Andre-Marie Ampere (1820)  Noticed the relationship between electricity and magnetism  Observed that a compass needle turns when it is near a wire carrying electric current  Amount of deflection depends on amount of current

Electromagnets (read pg. 310)  A strong temporary magnet, created by inserting a soft iron core into a coil of wire and then passing a current through the wire  Increase coils = strength of magnet increases  If current direction changes = so does the magnetic field Draw This!

Magnetism to Electricity  Electric effect can also be produced using a magnet  If you moved a wire at right angles to a magnet, it would produce a voltage (lights a light bulb!)  Ex: Figure 4.35 pg. 312  The connection between magnetism and electricity was used to develop motors, generators, and other electrical technology.

What’s in a Generator?  Electric Generator: device that converts mechanical energy into electric energy  Have a coil of wire that rotates inside a stationary field magnet  The coil is rotated by an external force  Ex: steam, falling water or wind  As the wires rotate, electrons begin to move along the wire in one direction.  This makes electricity!!!

AC/DC  DC  direct current  electrons move through the circuit in one direction only  you MUST have a split ring commutator so that the direction of current never changes  AC  Alternating current  electrons change directions  There are no gaps on the commutator  We use AC because it’s safer and more efficient.

What is a motor?  Motors: convert electrical energy into mechanical energy  Can be constructed in the same way as a generator  BUT instead of creating electrical energy it uses it!!

To do:  pg. 317 #1,2,3,4