true or false? the electrons in a circuit move in the same direction as the current. the current...
TRANSCRIPT
![Page 1: True or False? The electrons in a circuit move in the same direction as the current. The current through a component is directly proportional to the voltage](https://reader036.vdocument.in/reader036/viewer/2022072007/56649d345503460f94a0ac2d/html5/thumbnails/1.jpg)
True or False?• The electrons in a circuit move in the
same direction as the current.
• The current through a component is directly proportional to the voltage if the resistance of the component stays the same.
• The resistance in a wire is directly to the thickness of the wire.
![Page 2: True or False? The electrons in a circuit move in the same direction as the current. The current through a component is directly proportional to the voltage](https://reader036.vdocument.in/reader036/viewer/2022072007/56649d345503460f94a0ac2d/html5/thumbnails/2.jpg)
True or False?
• In a filament lamp the resistance increases with the voltage.
• The electrons lose part of the E.M.F. provided by the battery as they go around the circuit once.
• In a thermistor the resistance is higher when the weather is cooler.
![Page 3: True or False? The electrons in a circuit move in the same direction as the current. The current through a component is directly proportional to the voltage](https://reader036.vdocument.in/reader036/viewer/2022072007/56649d345503460f94a0ac2d/html5/thumbnails/3.jpg)
Resistance in Series and Parallel
• Resistance in series circuits
• Resistance in parallel circuits
![Page 4: True or False? The electrons in a circuit move in the same direction as the current. The current through a component is directly proportional to the voltage](https://reader036.vdocument.in/reader036/viewer/2022072007/56649d345503460f94a0ac2d/html5/thumbnails/4.jpg)
Resistance in series circuits
Use Ohm’s law to calculate the voltage across the resistors in the next slide.
Write your values in the voltmeters and see if they agree with the actual readings.
![Page 5: True or False? The electrons in a circuit move in the same direction as the current. The current through a component is directly proportional to the voltage](https://reader036.vdocument.in/reader036/viewer/2022072007/56649d345503460f94a0ac2d/html5/thumbnails/5.jpg)
.603
1.332
.897
2.2 Ω 1.5 Ω
VoltsVolts
Amps
![Page 6: True or False? The electrons in a circuit move in the same direction as the current. The current through a component is directly proportional to the voltage](https://reader036.vdocument.in/reader036/viewer/2022072007/56649d345503460f94a0ac2d/html5/thumbnails/6.jpg)
.601
2.231
2.2 Ω
1.5 Ω
Volts
Amps
What should the voltage across the two resistors be?
![Page 7: True or False? The electrons in a circuit move in the same direction as the current. The current through a component is directly proportional to the voltage](https://reader036.vdocument.in/reader036/viewer/2022072007/56649d345503460f94a0ac2d/html5/thumbnails/7.jpg)
Equivalent resistance
0.601 A
2.231 V
The two resistors in the previous series circuit can be thought of as a single resistor. Work out and write the equivalent resistance using Ohm’s law and the values of current and voltage shown.
3.7 Ω
![Page 8: True or False? The electrons in a circuit move in the same direction as the current. The current through a component is directly proportional to the voltage](https://reader036.vdocument.in/reader036/viewer/2022072007/56649d345503460f94a0ac2d/html5/thumbnails/8.jpg)
Equivalent resistanceIn a series circuit the total resistance of the components is the sum of the resistance of each component. So, the equivalent resistance R is found as:
R = R1 + R2
3.7 Ω2.2 Ω 1.5 Ω
R1 R2 R
![Page 9: True or False? The electrons in a circuit move in the same direction as the current. The current through a component is directly proportional to the voltage](https://reader036.vdocument.in/reader036/viewer/2022072007/56649d345503460f94a0ac2d/html5/thumbnails/9.jpg)
Look at the parallel circuit on the next slide and work out the current in the main circuit and through each resistor in the parallel branches.
Resistance in parallel circuits
![Page 10: True or False? The electrons in a circuit move in the same direction as the current. The current through a component is directly proportional to the voltage](https://reader036.vdocument.in/reader036/viewer/2022072007/56649d345503460f94a0ac2d/html5/thumbnails/10.jpg)
1.9911.830
1.716
2.2 Ω
1.5 Ω
Volts
Volts
Amps
What do you think the current in the main circuit should be?
1.144 A
0.832 A
![Page 11: True or False? The electrons in a circuit move in the same direction as the current. The current through a component is directly proportional to the voltage](https://reader036.vdocument.in/reader036/viewer/2022072007/56649d345503460f94a0ac2d/html5/thumbnails/11.jpg)
Resistance in parallel circuits
The current in the main circuit is the sum of the currents in the parallel branches:
I = I1 + I2
R1
R2
I
I1
I2
![Page 12: True or False? The electrons in a circuit move in the same direction as the current. The current through a component is directly proportional to the voltage](https://reader036.vdocument.in/reader036/viewer/2022072007/56649d345503460f94a0ac2d/html5/thumbnails/12.jpg)
1.9911.830
1.716
2.2 Ω
1.5 Ω
Volts
Volts
Amps
Work out the combined resistance in the main circuit with these values of current and voltage
![Page 13: True or False? The electrons in a circuit move in the same direction as the current. The current through a component is directly proportional to the voltage](https://reader036.vdocument.in/reader036/viewer/2022072007/56649d345503460f94a0ac2d/html5/thumbnails/13.jpg)
Using the values of V and I in the previous slide and Ohm’s law to work out the combined resistance, we find:
R1=2.2 Ω
I
I1
I2 R2=1.5 Ω
VI
1.8 V1.99 A
What can you notice about the combined resistance?
Combined resistance
R = = = 0.9 Ω
![Page 14: True or False? The electrons in a circuit move in the same direction as the current. The current through a component is directly proportional to the voltage](https://reader036.vdocument.in/reader036/viewer/2022072007/56649d345503460f94a0ac2d/html5/thumbnails/14.jpg)
Combined resistance
The combined resistance R = 0.9 Ω is less than R1 = 2.2 Ω or R2 = 1.5 Ω. You can work out the combined resistance of a parallel circuit using these formulae:
or
21
111
RRR
21
21
RR
RRR
What is the combined resistance when the resistors are the same?
![Page 15: True or False? The electrons in a circuit move in the same direction as the current. The current through a component is directly proportional to the voltage](https://reader036.vdocument.in/reader036/viewer/2022072007/56649d345503460f94a0ac2d/html5/thumbnails/15.jpg)
What is the equivalent circuit?
8 A
A
V
12 32
V V
2.5 A
A
V
8 A
12 32
V V
2.5 A
Split the branches in two separate circuits. What is this circuit?This is a series circuit where the current is 2.5 A (the reading inside the branch). What is the voltage across the two resistors?
V = R x I
3080
What is the equivalent circuit?
![Page 16: True or False? The electrons in a circuit move in the same direction as the current. The current through a component is directly proportional to the voltage](https://reader036.vdocument.in/reader036/viewer/2022072007/56649d345503460f94a0ac2d/html5/thumbnails/16.jpg)
What is the equivalent circuit?
8 A
A
V
12 32
V V
2.5 A
A
V
8 A
12 32
V V
2.5 A
What is the equivalent resistance and the voltage across?
3080
44
110
Now you can deal with this. What is the voltage, current and resistance?
110
5.520