Topic 6: Generators and Motors Science 9 with Mrs M Please take off your hats and hoods

Generating Power Most of our power comes from large power plants that convert mechanical energy into electrical energy Remember that question, “why are turbines so important?” We will answer that! Topic 6 Generators and Motors

Power Plant Turbine -> Generator The turbine provides enough force to turn the generator’s coil of wires Topic 6 Generators and Motors

Electric Generator Device that converts mechanical energy into electric energy Topic 6 Generators and Motors NOTES

Generators Electricity and Magnetism are related Topic 6 Generators and Motors NOTES NS

Electricity and Magnetism are Related Topic 6 Generators and Motors NOTES

How do we know? Compass needle turns when near electric field With more electricity there is a stronger needle deflection = stronger magnetic field Topic 6 Generators and Motors NOTES

Reverse the electric current and you reverse the direction of the magnetic field Stop the current = stop the magnetic field

Electromagnet When current is passed through a coil of wire wrapped around an iron rod an electromagnet is created North and south poles form on either end of the wire More coils = stronger magnet Topic 6 Generators and Motors NOTES

Topic 6 Generators and Motors Electromagnet from a soft iron core that becomes magnetic when current flows

Magnetized Material Water has a dipole (North and South) Alignment of “poles” is similar to the alignment of charges. Topic 6 Generators and Motors

MRI works on this principle (Magnetic Resonance Imaging) Topic 6 Generators and Motors

Earth has a magnetic field

The human heart’s electrical impulses create a magnetic field

Example of an electromagnet: Maglev Trains

Links Using iron filings to observe field of solenoid BIk4 BIk4 melt metal with magnets o9s0 o9s0 Make a Magnetic Field Qxg Qxg Topic 6 Generators and Motors

Question: How are electricity and magnetism related? Topic 6 Generators and Motors

How are electricity and magnetism related? Electricity and magnetism related because flowing electrons produce a magnetic field. Electricity and magnetism are ALSO related because spinning magnets can produce electricity. Topic 6 Generators and Motors

Electricity and magnetism are related: flowing electrons produce a magnetic field spinning magnets can produce electricity O68 O68 Motor: – electricity -> mechanical energy Generator: – magnet -> mechanical force -> electricity Topic 6 Generators and Motors

Motor: – electricity -> mechanical energy Generator: – magnet -> mechanical force -> electricity

AC Generators - External force rotates the coil - Coil of wire rotates inside of a stationary magnetic field - Most generators use electromagnets instead of permanent magnets - As coil’s wires rotate inside the field, electrons move Topic 6 Generators and Motors

AC: Alternating Current AC generators produce electricity that changes directions After one half-rotation of the coil, each side passes near the opposite pole of the magnet, and the electrons move in the opposite direction Topic 6 Generators and Motors

Benefits of AC current Easy to increase/decrease the voltage This helps set up voltage for power line transmission (more in Topic 7) Topic 6 Generators and Motors

DC Generators Current in only one direction Topic 6 Generators and Motors

Electric Motors Convert electrical energy to mechanical energy Topic 6 Generators and Motors

Exploratory Stations Generator Motor Electromagnets Piezoelectric crystal Bar magnet’s field lines Topic 6 Generators and Motors