23 terms

Electricity

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Voltage
Definition: The electrical potential energy per charge.
Unit: Joules/Coulomb=Volts
Voltmeter
Definition: A mechanism that measures the difference in voltage between two points on a wire
Units used: Volts
Current
Definition: A measure of the amount of electrical charge transferred per a given unit of time.
Unit: Coulombs/Second=Amperes
Current Meter
Definition: A mechanism that measures the current through a given portion of wire.
Units used: Amperes
Which way do electrons flow? Why?
From the negative terminal, to the positive terminal-- because, as they are negatively charged, they are attracted to the positive terminal. Furthermore, at the negative terminal they have more EPE than at the positive terminal-- the more distanced they are from the place "where they want to be", the more EPE they have.
Which way does current flow?
From the positive terminal to the negative terminal; opposite the flow of electrons.
What is the formula for electrical power? What are the units?
Formula: Power=Current*Voltage
Units: Watts
What is Ohm's law? What is the formula?
Definition: Current in a circuit is directly proportional to the voltage impressed across the circuit and is inversely proportional to the resistance of the circuit.
Formula: Current=Voltage/Resistance
Resistance
Definition: Resistance of a material to the flow of electric charge through it
Unit: Ohms
Direct Current (DC)
The flowing of charges (current) in one direction in a circuit.
Alternating Current (AC)
Electric current that rapidly reverses in directions. The electric charges vibrate about relatively fixed positions.
Fuse
A line of wire designed to melt and separate in the event of excessive current, protecting the rest of the circuit from potential problems due to the amount of energy.
Circuit Breaker
A switch that automatically interrupts or shuts off an electric circuit at the first indication of an overload of current.
Kirchoff's Voltage Law
The total of all the potential differences around a closed path of a circuit must be equal to zero.
Kirchoff's Current Law
The current that enters into a branch is equal to the current that comes out of that same branch.
Which charge does red wire represent? Black?
Red represents the positive terminal, while the black represents the negative.
Capacitor
An electronic device that can maintain an electrical charge for a period of time and is used to smooth out the flow of electrical current--especially when there is a break in the current. Capacitors are often found in computer power supplies.
When first connected, a capacitor acts like______. After it is charged up, it eventually acts like a _________.
Unbroken wire, broken wire.
Why does current stop almost instantly in a broken wire?
Because there is a build-up of positive charge the end of the broken wire, repelling the incoming current.
What are two ways in which we could make a current flow for longer in a broken circuit?
Extend the limitations of the wire by placing capacitors, or make the gap smaller.
In a circuit, where is the voltage higher? Where is the voltage lower?
The voltage is higher near the positive terminal, while it is lower near the negative terminal.
What is the formula for power? What are the units?
Formula: Power=Work/Time or Power=Change in Energy/Time
Unit: Watt
What are the two things that play into the brightness of a bulb?
Current and Voltage