Test 3- Electrodynamics Second Powerpoint Flashcards
Define Electricity:
The continuous flow of electrons along the surface of a conductor
Define Electrodynamic:
The study of flowing electrical current
Define Current:
The flow of loosely-bound, outer shell electrons when a potential difference (voltage) is applied
Define Conductivity:
A materials ability to transmit electrical current
A conductor is, any material through which energy flows easily
Conductors allow electricity to pass through easily
Give some examples
Copper
Sliver
Aluminum
Brass
Water
Insulators (dielectrics): Resist the flow of electricity
Give some examples
Rubber
Glass
Plastic
Dry wood
Symbols and Functions of electric circuit
elements
Slide 9
(Make Quizlet)
Although we usually think of electrical current as a steady flow of electrons, at the atomic level…. What we we think of it as?
Loosely bound electrons in the outermost shells actually “Leap Frog” from one atom to the next in sequence
Current is:
Mathematically, the rate of flow of electrons
Electrons per second
Coulombs per hour
Circuit=
Circle!
To have a circuit, conductors must pass from the voltage source (battery) through all devices and back to the source.
If the circuit is broken at any point, electricity stops flowing throughout the circuit
Does a battery create electrons?
No!
It only pumps them out one end and pulls them in from the other end.
This pumping movement fails if the circuit is not complete
To have a circuit, at least 3 components are required:
1) A Conductor
2) A source of EMF (electromotive force)
3) A device to be operated that acts as an electrical resistor in the circuit
An electrical switch is just a method of ___
Breaking the circuit
What are the two general types of circuit layouts?
Example them
1) Series- All decided are connect in a row, one after another along the same wire
- If one device burns out, the entire circuit is broken and current stops
2) Parallel- Devices are connected each in a separate brand of the wire, which splits off from the original conductor
- Other branches of the circle are unaffected if one device burns out
* Christmas lights are a good example
The relationship between electrical resistance, pressure and flow are described by the formula:
V= IR
V= Voltage
I= Amperage (current)
R= Resistance in a particular circuit
OHM’S LAW FORMULA
Voltage and current are ____ to each other
Directly Proportional
- if pressure doubles, the amount of current flowing doubles
Voltage and resistance are ____ to each other
Directly Proportional
- To maintain the flow, If resistance is doubled, pressure must also be doubled
Amperage and resistance are___ to each other
Inversely Proportional
If resistance doubles, the amount of current flowing is cut in half
Power, in general is defined as the rate at which:
Work is done
Direct Current:
Electrons always flow in the same direction in a steady stream
Alternating Current (AC):
Electrons oscillate back and forth
Electric Generators:
Convert mechanical energy into electric charge
A current is inducted in a conductor that is moved through a magnetic field ___ or ___ to the magnetic field lines
Across or Perpendicular
If the conductor moves ___ to the magnetic field, there is no current induced in the conductor.
Parallel
AC Generator
kVp=
peak voltage
A motor converts ____ into ___
electric charge into mechanical energy
Generators convert ___ into ____
Mechanical energy into electrical energy
What are the two part to every motor?
The Rotor: Spins
The Stator: Stationary coils of wire surrounding the rotor
What is an induction motor?
What do transformers do?
Alter the voltage or the amperage of electrical current
Mutual induction occurs when:
Two coils are placed in proximity and varying current supplied to the first coil (primary) induces a similar flow in the second coil (secondary)
The unit of mutual inductance is the:
Henry
Mutual Induction
Flow occurs in secondary coil because the ___ current alternates.
Primary
What is the phenomenon in which a change in electric current in a coil produced an induced emf in the coil itself?
Self Induction
Self inducted emf in a foul is ____ to the rate of change of electric current in the coil.
Directly Proportional
Transformers consists of:
a pair of wire coils joined together around an iron core
Transformers
Transform ____ and current into higher and lower intensities.
Electric Potential
What is used to change low voltage into higher voltages or vice versa in an AC circuit?
A transformer
___ transformers have a turns ratio greater than 1
Step Up Transformers
___ have turns ratio less than 1
step down transformers
What are the three types of transformers?
Closed-core transformer
Auto transformer
Shell type transformer
Review Summary Slides at the end of
