Electricity Flashcards
Coulomb
Is a quantity measurement for electrons. Measurement of electric charge
Ampere
Standard measurement of electrical current.
Volt
The potential difference between two point of a conducting wire carrying constant current of one ampere when the power dissipated between these points is one watt
Electromotive Force (EMF)
Another name for voltage
Potential Difference
Another name for voltage
Coulomb force is repulsive
If polarities are the same
Coulomb force is attractive
Polarities are opposite
Coulomb force decreases
In proportion to the square of the distance between their charge centers
Ampere (A)
Is equal to one coulomb per second. Is the measurement of the amount electricity that is flowing through a circuit.
What must be present before current can flow
Voltage
Voltage cannot flow. Voltage pushes current through a wire.
The unit of resistance to current flow. All electric loads are measured in this
Ohm’s
___ is a measure of the amount of power that is being used in a circuit.
Wattage / Watt
____ is proportional to the amount of voltage and the amount of current flow.
Wattage
Factor of volts times amps
Watts
A voltmeter is hooked up in _____ to measure voltage in a circuit.
Parallel
An ammeter is hooked up in _____ to measure current in a circuit.
Series
The circuit MUST be de-energized prior to reading _____?
Resistance
____ is a very good way to check continuity of a circuit.
Resistance Measurement
All wire has ____
Resistance
Factors that determine how much resistance is added.
Type of material from which the wire is made.
Diameter of the conductor, or size of conductor.
The length of the conductor.
The temperature of the conductor.
Current flow requires
Complete Path - Circuit (amps)
Push - Voltage
All current on a circuit must return to its source
Current flow
Short Circuit Current - returns to the source through the neutral and earth
Fault current
Neutral current kept low, then voltage on neutral is low
Neutral current
Neutral voltage increases when neutral line resistance increases
Neutral line resistance
A ____ or ____ in the neutral wire introduces an infinite resistance.
Break and open
Body resistance
Dry hand to dry hand = ____
Damp hand to damp hand = ____
Internal Organs = ____.
100,000 ohms
35,000 ohms
100 to 400 ohms
Average workers skin resistance is broken down by approximately __ volts
50
____ wires must always be jumpered before opening.
Neutral
What are the two theories concerning current flow
Electron flow theory
Conventional current flow theory
The _____ theory states that since electrons are negative particles, current flows from the most negative point in the circuit to the most positive point
Electron Flow Theory
The ______ theory is the one most often used and states that current flows from the most positive point to the most negative.
Conventional Current Flow
____ states that it takes one volt to push one ampere through one ohm.
Ohm’s Law
All ____ quantities are proportional to each other and therefore can be expressed as mathematical formulas.
Electric
What are the three types of electrical circuits
Closed Circuit
Short Circuit
Grounded Circuit
When current flows through a conductor, a ______ is created around the conductor.
Magnetic field
When a conductor is cut by a magnetic field, a _____ is induced in the conductor.
Voltage
The ____ of the world induced voltage is determined by the ____ of the magnetic field in relation to the direction of motion.
Polarity
What are the three factors that determine the amount of induced voltage?
Number of turns of wire
Strength of the magnetic field
Speed of the cutting action
_____ ______ is always opposite in polarity to the applied voltage
Induced voltage
Inductors ____ a change of current
Oppose
Inductors can produce extremely ___ voltages when the current flowing through them is stopped
High
Three devices used to help prevent large voltage spikes are
Resistors
Varistors
Diode
____ is the total opposition to current flow in an electric circuit
Impedance
In a pure inductive circuit, the _____ lags the _____ by 90 degrees
Current, voltage
In a pure inductive circuit, however, no true power or watts is produced.
Inductive circuit
An electrical measurement called _______ is used to measure the reactive power in a pure inductive circuit
Volts-amperes-reactive (VARS)
_____ voltage is proportional to the rate of change in current
Induced
Induced voltage is always ____ in polarity to the applied voltage
Opposite
Series Circuit Rules
Current = same at any point in circuit
Resistance total = sum of all resistors
Voltage (E) = sum of voltage drop across all resistors (load)
Parallel Circuit Rules
Current (It) = sum of the current that flows thru the individual branches
Resistance = < the resistance of the lowest value of resistors or branch in circuit. (Reciprocal resistors)
Voltage (E) = voltage drop is the same as applied voltage.
Prefix - micro (ų)
0.000,001
Prefix - kilo (K)
1,000
Prefix - mega (M)
1,000,000
Prefix - milli (m)
0.001
All values of a transformer are proportional to its _____
Turn ratio
The power value for a capacitor is measured in ____
VARS
A meter reads 122 volts AC when plugged in at a wall outlet? This voltage is ____
RMS
A capacitor store energy in ____
Electrostatic field
Current can flow only when a capacitor is _____ or _____
Charging
Discharging
Principal parts of a atom
Electrons
Protons
Neutrons
Protons have a _____ charge
Positive
Electrons have a ____ charge
Negative
Neutrons have ____ charge
No
What law states opposites charges attract and like charges repel
Law of charges
What is the flow of electrons
Electrons current
_____ is produced when an electron from one atom knocks electrons from another atom out of orbit
Electron current
Materials that permit electrons to flow through them easily
Conductors
Materials that resist the flow of electrons
Insulators
Electrons in the outermost electron orbit
Valence
Materials that contain between 1 and 3 valence electrons l
Conductors
Materials that contain 7-8 valance electrons
Insulators
Most common method to used to produce electricity
Magnetism
Static electricity is a charge because there is no current flow until it is ____
Discharged
Six basic methods of producing electricity are
Magnetism
Chemical action
Light
Heat
Pressure
Friction
A ________ occurs when a path to ground other then the intended path is established
Ground fault
What is the most importance rule of electrical safety?
Do not become the victim yourself
______ are devices that oppose a change in voltage
Capacitors
What are the three factors that determine the capacitance of a capacitor are
The surface area of the plates
The distance between the plates
The type of dielectric used
A capacitor stores energy in an ________
Electrostatic field
The basic unit of capacitance is the _____
Farad (F)
When capacitors are connected in _____, their capacitance values add
Parallel
When capacitors are connected in series, the _____ of the total capacitance is equal to the sum of the ______ of all the capacitors
Reciprocals
When a ______ is connected in an AC circuit, current appears to flow through the _____?
Capacitor
The current flow in a pure capacitive circuit is limited by _____ _____?
Capacitive reactance
Capacitive reactance is _____ ______ to the capacitance of the capacitor and the frequency of the AC line
Inversely proportional
Capacitive power is measured in ____, as in inductance.
VARs (Volt-Amp Reactive)
In pure capacitive circuit, the current leads the applied voltage by ___ degrees
90
