Electricity 2 Flashcards
An electric circuit consists of ________, _________, and ________.
- A power source 2. Conductors 3. A load
A ______ is any device that uses electric energy.
Load
EMF is measured in _____.
Volts
2 factors determine how much current will flow in a DC circuit, ______, and _______.
Applied voltage and conductance of the wires and the load
is how easily electricity flows in a circuit.
Conductance
______ has the greatest conductance.
Silver
Resistance of a material (element) depends on ________.
The number of free electrons it has
The greater the cross-sectional area of a conductor, the _____ the resistance.
Lower
The resistance of the load is normally much _____ than the wiring.
Greater
Every power source has some internal ________.
Resistance
The longer the conductor, the _____ the resistance.
greater
The materials most often used for resistors are
carbon, and metal alloys such as nichrome, contantan, and manganam.
Resistors are marked with a
tolerance.
Current rating is often given in
wattage.
Composition resistors have the advantage of _____, _____, _____.
small size, ruggedness, and low cost.
Precision-type, wire-wound resistors have very ____ tolerances.
small
The property of maintaining a small tolerance under all operating conditions is called
stability.
When all three terminals of a variable resistor are connected in a circuit, it’s called a
potentiometer.
When only two terminals are connected in a circuit, it’s called a
rheostat.
Power is
work per second.
1 watt =
1 Joule per second/ 1 amp x 1 volt
Power ratings are not based on I2R losses, but rather on power they are able to use to do _______.
mechanical work
Total power consumed is rated in
KWHRs.
In a series circuit, current is
constant, so there are drops in voltage.
When two batteries are connected in series, the negative terminal is connected to the positive terminal of the other battery. Current flows from the ______ to the ______ terminal.
negative, positive
In a series circuit, total voltage is equal to _____.
The sum of the individual voltages
If batteries are connected negative to negative, their voltages will _____.
cancel
Total voltage drop in a series circuit equals
source voltage.
A ______ exists if power flows from the negative terminal to the + terminal without going through a load.
short circuit
The electromagnetic circuit breaker uses _______ to to open and close the circuit.
magnetism
A parallel circuit has
more than one path for current to flow.
In a parallel circuit, total current equals
the sum of the individual currents.
In a parallel circuit, the _____ method is used to find total resistance.
reciprocal
Total power consumption can be found by ________.
adding up the individual power consumptions of the circuit
Kirchhoff’s first law is
the sum of the voltage drops around any closed loop is equal to the sum of the EMF’s in that loop.
Resistors usually fail because
of heat generated by the circuit.
