physics 12 mr. jean may 7 th, 2014. the plan: video clip of the day ac/dc power generation
TRANSCRIPT
Physics 12
Mr. JeanMay 7th, 2014
The plan:
• Video clip of the day• AC/DC power generation
Introduction to DC Power & Motors:
• DC Power and Motors– http://www.youtube.com/watch?v=OpL0joqJmqY
AC Generators:
• Generators are essentially the same design as motors. – The mechanical energy input to a generator turns the coil
in the magnetic field. This produces an emf (voltage). A sinusoidal voltage output.
• The mechanical energy may come from:– i. Steam– ii. Wind– iii. Waterfall
DC Generator: • The commutator must change the AC flowing
into its armature into DC.
• Commutators keep the current flowing in one direction instead of back and forth.
Power Production
• Generators were built by Tesla to generate electricity reliably and in large quantities.
• Most of today’s energy sold is in the form of AC because it can easily be transformed from one voltage to another.
High Voltage with Low Current:
• Power is transmitted at high voltages and low current without much energy loss (heating of wire) because it can be stepped down from the plant to many cities, to a city, to the household.
• Household typical outlet is 120 V AC.
Transformers: • Transformers are used to transfer energy from
one circuit to another by means of mutual inductance between two coils.
Types of Transformers:
• Transformers consist of a primary coil (input) and a secondary coil (output).
• Step-up Transformer – Secondary has more turns – greater electric potential (V) induced, caused by
the lowering for current (I)
Types of Transformers:
• Transformers consist of a primary coil (input) and a secondary coil (output).
• Step-down Transformer – primary has more turns– Thus less electric potential (V) induced causing a
greater current (I).
Transformers:
• Transferring energy from one coil to the other OR the rate of transferring energy is the power.
• The power used in the secondary is supplied by the primary.
• LAW OF CONSERVATION OF ENERGY
Transformers:• Brightstorm: Transformers– http://www.youtube.com/watch?v=4aYhAbzSwvs