Basic Electrical Theory I
What force causes electrons to flow? What is another name for it?
EMF, Voltage
What formula is used to find resistance in a parallel circuit?
Total Parallel Circuit:
RT=1/(R1)+1/(R2)+1/(R3)...
If the reciprocal of both sides is taken:
RT=1/(1/(R1)+1/(R2)+1/(R3)
Which type of power can be easily stored?
DC
What is ohms law?
E=IxR
Voltage=Current x Resistance
What type of power is created by spinning machines?
AC
This type has stator windings.
Generator
Alternator
Does a multimeter typically read peak voltage or RMS? Briefly define RMS?
RMS; Root mean square - it's the measurement of current that takes into account that AC current has peaks and valleys, and that the peaks and valleys don't represent useful current.
What formula is used to find the total resistance in a series circuit?
RT=R1+R2+R3...
What is the advantage of using AC instead of DC?
1. It is easier to step up or down the voltage.
2. Higher voltage can be used (lighter wires).
3. AC motors are smaller and lighter
In a series circuit is the amperage the same or different everywhere in the circuit?
The same
Give an example of a device (common in aviation) that generates voltage from heat.
Thermocouple
If an AC circuit is purely resistive, what else is true of the circuit?
It's in phase
What is Static and Current Electricity? Describe each one.
Static Electricity - Stationary electrical charge.
Current Electricity - Useful type with actual flow.
What two components are needed to generate AC electricity? What must happen between them to generate electricity?
Inductor and magnet. Relative motion.
What is Inductive Reactance?
The opposition of current flow...
This is also known as Counter EMF and it will caules phase shifting...
What do we call the opposition to flow caused by inductors and capacitors?
Reactance
How does a load cell generate electricity?
By squeezing a crystal that has piezoelectric properties
What makes a material a good conductor?
It has valence electrons that are very willing to detach and move from atom to atom.
What are the five different methods of creating electricity?
Chemical, Heat, Light, Pressure, Magnetism
What are the three things needed for electromagnetic induction to work?
Electromagnet
Voltage (EMF)
Relative Motion
What is Phase Shifting and how is it controlled?
In AC circuits, the Voltage and Current may not reach the same amplitude peaks at the same time, they generally have a difference in timing. That difference in timing is called Phase Shift and is controlled with a control on the outside of some generators that are series wound...
Explain Faraday's Law
Relative motion between a wire and a magnetic field generates an electromotive force and a flow of current in a closed circuit
How many kilo hertz is 350,000 hertz?
How many miliohms is .003 ohms?
350
3
All the opposition to flow in an AC circuit from resistors, capacitors and inductors
During the process of electromagnetic induction, the value of the induced voltage/current depends on three basic factors...
1. Number of turns in the conductor coil (more loops equals greater induced voltage).
2. Strength of the electromagnet (the stronger the magnetic field, the greater the induced voltage).
3. Speed of rotation of the conductor or magnet (the faster the rotation, the greater the induced voltage).
Describe Impedance, what letter represents it?
The total opposition to current flow in an AC circuit is known as impedance and is represented by the letter (Z).
The outflow valve of a 737 can be actuated by either of 2 AC motors or a DC motor. The DC motor runs off battery and is used in emergency situations. If this is a ½ hp motor that is 80% efficient and the battery is providing 28 volts, what amount of resistance is created by the motor?
1.68 Ohms
What is the difference between electron current and conventional current?
Electron current goes from the negative terminal, it is the actual flow of electrons in a circuit.
Conventional current Is an imaginary flow of electricity that flows from the positive terminal to negative.
Pg. 497
Explain ELI the ICE Man
Voltage leads current in an inductive circuit; Current leads voltage in a capacitive circuit.