Intro to Electronics
Technology 7
Mr. O’Rourke
How it Works:
• Electricity is a flow of sub-atomic (very, very
small) particles, called electrons.
• Electrons move from a atom to atom when an
electrical charge is applied across the material.
Water/Pipe Analogy:
• Wires: can be thought of as smooth pipes that
allow water to pass through easily.
– Usually made of copper, which offers low
resistance to the flow of electricity
Electric current, expressed in amperes is a measure
of how fast the current (or water) is flowing through
the wire (pipe).
The Battery:
• To make water flow through a pipe, we need a
pump. This is accomplished through the use
of a battery or other power source.
Voltage:
• Expressed in volts. A measure of how strong
the electric charge from your power source is.
• + or – indicate which direction electricity
(water) will flow.
The Switch:
• Similar to a faucet or valve, you use a switch
to turn the electricity off in your circuit.
• A switch connects (closed or on) or
disconnects (open or off) the wires in your
circuit.
Resistors:
• Why is the water pipe that goes to your
kitchen faucet smaller than the main supply
line to your house? Because you don’t need
as much water at that location.
• Pipe size limits the water flow.
• Similar to electricity, except that wires have so
little resistance, they would have to be super
thin (brittle) to limit the flow of electricity.
Resistors (cont’d):
• Water flow through a large pipe could be
limited by clogging the pipe with an object
(rocks), which would slow the flow but not
stop it.
• Resistors are like rocks, resistance is measured
in ohms.
• Lower value resistor increases current
Things to Remember:
• Electrons are the particles that flow between
atoms as part of an electrical current.
• A short circuit occurs when wires or components
from different parts of the circuit accidentally
connect.
• A battery produces electricity using a chemical
reaction.
• To decrease the current in a circuit you may
decrease the voltage or increase the resistance.
Cont’d:
• Materials which have very high resistance are
called insulators, materials with very low
resistance are called conductors.
• Adding resistors in parallel decreases
resistance, while adding resistors in series
increases resistance.
• The electrical resistance of water decreases
when salt is dissolved in it.
Cont’d:
• Capacitors are components that can store
voltage for periods of time.
• Capacitors have low resistance to alternating
current and high resistance to direct current.
• Adding capacitors in parallel increases the
capacitance while adding capacitors in series
decreases the capacitance.