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ELECTRICITY
Electric current – the rate at which
charges pass through a given point
*Measured in amperes (amps)
Two kinds
•Direct current (DC) – charges flow in the same
direction (ex. a battery)
•Alternating current (AC) – charges continually
shift from one direction to the reverse direction
(ex. The outlets in your home)
Conductor – substance that readily
conducts electricity; allows electricity
to pass through (ex. metal)
Insulator – substance that does not
readily conduct electricity; does not
allow electricity to pass through
(ex. plastic)
Electric circuit – a complete, closed path
through which electric charges flow.
*If the path is broken, it is called
an open circuit.
3 basic parts of a circuit
1. energy source
2. wires
3. a load (such as a light bulb).
Two types of circuits
* Series circuit – all parts are
connected in a single loop; only one
path for charges to flow through.
* Parallel circuit – loads are connected
side by side; more than one path
for charges to flow through.
Voltage – the potential difference
between two points in a circuit
* a measure of how much work is
needed to move a charge between
two points
* the higher the voltage is, the more
energy is released per charge
Resistors – devices that slow the flow of
current in a wire.
* measured in in units called ohms
Ohms’s Law – the relationship between
voltage, current, and resistance in a
circuit.
* V (voltage), R (resistance, I (current)
Ohm’s Law Equations
voltage = resistance X current
resistance = voltage/current
current = voltage/resistance