2. What are Circuits?
• When plug and wires connect an electrical
outlet to a string of light bulbs, electrical
charges have a complete path to flow.
• The bulb, electrical outlet, and wires form an
Electrical Circuit.
3. Closed and open Circuits:
• Closed Circuit: is a complete path.
• Open Circuit: when there is no complete path.
• The voltage source, whether a battery or an
outlet, is always part of the conducting path of
a closed circuit.
4. Switches interrupt the flow of charges
in a circuit.
• You use a switch to open or close a circuit, as
you have probably done many times. Switches
are used to turn lights on and off. You either
close or open a circuit to turn a light on or off.
• Electrons can move through the bar to reach
the other side of the switch. If the metal bar
on the switch is lifted, the switch is opened.
5. Schematic diagrams are used to
represent Circuits.
• A diagram that depicts the construction of an
electric circuit or apparatus is called a
schematic diagram.
• All electric devices, from toasters to
computers, can be described by schematic
diagram.
6. Schematic diagrams use standard
symbols.
• Each element used in a piece of electrical
equipment is represented by a symbol that
reflects the elements construction or function.
• The symbol in the schematic diagram that
represents an open switch resembles the knife
switch.
