Equivalent Resistance, Volts, Amps. Volts and Amps in a Series Circuit In a series circuit, the...
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Transcript of Equivalent Resistance, Volts, Amps. Volts and Amps in a Series Circuit In a series circuit, the...
Equivalent Resistance, Volts, Amps
Volts and Amps in a Series Circuit
In a series circuit, the Amps remain constant throughout the whole circuit
Amps = 2A
Amps = 2A
Amps = 2A
Volts and Amps in a Series Circuit
However, in a series circuit at each resistor the volts change. When you add up all the voltage at each resistor, you end up getting the total volts going through the circuit.
Amps = 2A
Amps = 2A
Amps = 2A
Volts2 = 3V
Volts1 = 2V
Volts3 = 2VVolts
total = 7V
Volts and Amps in a Parallel Circuit
In a parallel circuit, each line of wire has a different amount of amps. When added the amps together, you get the total amount of amps in the entire circuit. Amps3
= 1A
Amps2 = .5A Amps3
= .5A
Amps tot = 2A
Volts and Amps in a Parallel Circuit
However, in a parallel circuit if you have a total of 3 volts in the circuit, each resistor will only have 3 volts
Amps3 = 1A
Amps2 = .5A Amps1
= .5A
Volts Total = 3V
Volts1 = 3V
Volts2 = 3V
Volts3 = 3V
Amps tot = 2A
Equivalent or Total Resistance - Req
Equivalent Resistance is the TOTAL resistance of a circuit Symbol: Req or Rt
Units: Ω Ohms Formula:
Series:
Req = R1 + R2 + R3 + …
Parallel:
...3
1
2
1
1
1
Re
1
RRRq
5
3 10
Type of circuit: Series
Formula: Req = R1 + R2 + R3
Req = 10 + 5 + 3
Req = 18
What is the equivalent resistance (Req) of the circuit below?
30
75
Type of circuit: Series
Formula: Req = R1 + R2
Req = 75 +30
Req = 105
What is the equivalent resistance (Req) of the circuit below?
Type of circuit: Parallel
Formula:
What is the equivalent resistance (Req) of the circuit below?
10 Ω
15 Ω
21
11
Re
1
RRq
1 ÷ 0.1666 = 6Ω
15
1
10
1
Re
1
q
0666.01.0Re
1
q
1666.0Re
1
q
6Req
Type of circuit: Parallel
Formula:
What is the equivalent resistance (Req) of the circuit below?
321
111
Re
1
RRRq
1 ÷ 0.3333 = 3Ω
15
1
5
1
15
1
Re
1
q
0666.02.00666.0Re
1
q
3333.0Re
1
q
3Req
15
5
15
KEY POINTS
321 R1
R1
R1
Req1
Symbols of circuit parts: Voltmeter, Ammeter, Power Supply, Resistor
Two types of circuits (series and parallel) Formula for Req (equivalent resistance)
Series – Req = R1 + R2 + R3
Parallel -
All the Information you need
Simulations
Open up applications for simulation Or go to
http://phet.colorado.edu/en/simulations/category/physics
Colour coding on resistors
Resistors are coated with ceramic.
They have color coded bands to indicate resistance
1st & 2nd band first two digits of resistance
3rd band Number of zeros to add after the first two numbers. I.E. 101, or 2, or 3….
Resistor
Example: If you have a resister that is red, orange and yellow
Black 0
Brown 1
Red 2
Orange 3
Yellow 4
Green 5
Blue 6
Violet 7
Gray 8
White 9
First colour is red, thus first digit is 2 and the
second colour is orange, thus the second digit is 3
= 23
The third colour is yellow, and this digit is 4 we therefore find 104 =
10000
This resistance would be 10000 X 23 = 230 000