20.1 electric circuits
DESCRIPTION
20.1 Electric Circuits. pp. 730 - 735 Mr. Richter. Agenda. Warm-Up Notes: Circuit Diagrams Electrical Circuits and Short Circuits Using the Multimeter. Objectives: We Will Be Able To…. Draw and interpret circuit diagrams. Build a circuit given a circuit diagram. - PowerPoint PPT PresentationTRANSCRIPT
20.1 Electric Circuitspp. 730 - 735
Mr. Richter
Agenda
Warm-Up Notes:
Circuit Diagrams Electrical Circuits and Short Circuits
Using the Multimeter
Objectives: We Will Be Able To… Draw and interpret circuit diagrams. Build a circuit given a circuit diagram. Use the multimeter to measure voltage and current in
a circuit.
Warm-Up:
At your table, use the whiteboard to draw a circuit that contains: 1 light bulb 1 resistor 1 open switch 2 batteries
When you are finished, bring your whiteboard to the front of the room.
Schematic Diagrams
Schematic Diagrams
Schematic diagrams, often called circuit diagrams, are used to represent the design of electrical circuits. Like force diagrams represent forces.
Electric Circuits
Electric Circuits
An electric circuit is a path through which electricity can be conducted.
All circuits contain two parts: a potential difference: what
supplies the energy (voltage) a load: an element or group of
elements that uses the energy
Conservation of energy: the voltage (energy in) must equal the load (energy out.
Electric Circuits
Switches are used to turn electricity on and off.
If a switch is on (connected), the circuit is closed, and electricity is flowing.
If a switch is off (unconnected), the circuit is open, and the flow of electricity is stopped.
Also happens with broken devices.
Electric Circuits
A short circuit is a path (often accidental) in a circuit that has a resistance close to zero.
Low resistance means high current. High current means lots of extra
heat. Extra heat can mean: melting burning exploding DANGER!
Electric Circuits
To prevent wires from drawing too much current (short circuiting) we use:
Circuit Breakers – flips the switch to off when the current gets too high
Fuses – actually breaks when current is too high
Measuring Voltage and Current
Measuring Voltage and Current
At your table, build the circuit below. When you’re done, check in with Mr. Richter
Measuring Voltage
A multimeter is used to measure voltage, current and resistance in a circuit.
To measure voltage: set the multimeter to
Volts. Red lead in the middle.
Touch probes to either side of an element to see the voltage gain or drop.
Red lead is always more “downstream.”
Voltage is a difference in potential energy. If energy is gained from black
to red, voltage should be positive.
Energy lost = negative voltage No change in energy = 0 volts.
Measuring Current
To measure current: set the multimeter to mAmps Red lead on the left. Current is always positive!
You must run your circuit THROUGH the multimeter. It counts how many electrons
pass by, like a ticket counter.
Wrap-Up: Did we meet our objectives?
Draw and interpret circuit diagrams. Build a circuit given a circuit diagram. Use the multimeter to measure voltage and current in
a circuit.
Homework
p. 735 #1-5