Electric Current
Name the two types of electricity.
Static
Current
This is the measure of the force with which an electric current flows, may also be referred to as electric potential or emf)
Voltage
Define a conductor and give a few examples of good/fair conductors
Conductor: materials through which current flows easily
Good: silver, copper, gold, aluminum
Fair: carbon, salt water
Define an electric circuit, making sure to reference the THREE parts
Electric circuit: the path that an electric current follows which has three parts--a source of current (battery/generator), conductors (wires to carry electrons around the circuit), and a load (which transforms energy of the current into another useful form of energy example: light, heat, sound waves, motion)
Current electricity can be subdivided into either of these two types, depending on how it flows
DC (direct current)
AC (alternating current)
What is the SI unit of voltage and after whom is it named and what instrument would you use to measure voltage.
volt (V)
Alessandro Volta
Voltmeter
Define an insulator and give examples of good insulators.
Insulator: materials through which current doesn't flow easily (they are good to insulate objects from electric currents)
Good: rubber, glass, dry wood, porcelain, plastic
What is the difference between a closed and an open circuit?
Closed circuit: a circuit that contains a complete path or 'closed loop' for the electrons to flow from the source through the load and back to the source again
Open circuit: a circuit where a 'gap' has been created thus electrons are not able to cross it and current flow ceases
Define DC current and give an example of where it is commonly used.
Direct Current: electricity that flows in only one direction, without reversing it.
Used in battery-powered devices, car electrical systems, computers
Define amperage. What is the SI unit of amperage?
Amperage: the number of coulombs of electric charge that pass a given point in one second or the amount of electron current. *remember: it is a rate of flow*
SI unit: ampere (A)
What is a semiconductor? Give an example of one semiconductor. Name how you would use a semiconductor.
Semiconductor: a material that is neither a good conductor nor a good insulator
Examples: silicon, germanium
Use: electronics
What device can be used to control a circuit?
Define AC current and give an example of where it is commonly used.
Alternating Current: electricity that flows first in one direction and then the other, reversing at regular intervals.
Used in our homes
How does power relate to both voltage and amperage? What is the SI unit of power?
The total power of an electron current is directly dependent on BOTH voltage and amperage.
SI unit: watt (W)
Define resistance. What is the SI unit for resistance?
Resistance: is the amount a certain object or material hinders electron flow (can also be thought of as the electrical 'friction' offered by a conductor to the flow of electric current)
*remember: good conductors have LOW resistance, while good insulators have HIGH resistance*
SI unit: ohm
Define a short circuit.
Name TWO devices that may be used to prevent circuits from overheating as a result of faulty wiring, overloads, or short circuits.
Short circuit: occurs when electricity is given the opportunity to take a 'short cut' through a circuit, thus avoiding the load
Devices: fuses, circuit breakers
What causes electrons to flow?
Electrons move from one place to another as a result of the attraction and repulsion between electric charges.
How do electric companies charge for electricity?
They charge by the kilowatt-hour (kW hr)
There are FOUR factors that affect resistance, name them.
Define a superconductor.
Define a resistor.
1-type of material
2-diamete of the conductor
3-length of the conductor
4-temperature
Superconductor: a material that allows current to flow through it with no resistance at all
Resistor: an electrical device designed to add resistance to a circuit
Explain the difference between circuits laid out in series versus circuits laid out in parallel.
Series circuit: the loads are arranged so that the electric current flows through each load, one after another. The current MUST flow through each load in order to get to the next one. *remember-the resistances of individual loads add to each other*
Parallel circuit: the loads are arranged in separate branches of the circuit and the current is divided among them. Thus, current flows through all the loads simultaneously.