Series Circuit
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In a series circuit, the current at any points of the circuit is the same.
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Parallel Circuit
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If the resistance of the 2 resistors is the same, current will be divided equally to both of the resistor.
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Series Circuit
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The sum of the potential difference across individual resistor in between 2 points in a series circuit is equal to the potential difference across the two points.
Example
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Parallel Circuit
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The potential difference across all resistors in a parallel circuit is the same.
Example
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Finding Current in a Series Circuit
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- In a series circuit, the current flow through each of the resistor is equal to the current flows through the whole circuit.
- Potential difference (V) across the whole circuit is equal to the e.m.f. (E) if the internal resistance is ignored.
- Effective resistance for the whole circuit = R1 + R2
- By Ohm’s Law
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For the circuit in the diagram above,
- find the reading of the ammeter.
- find the current flows through the resistor.
Answer:
a.
Potential difference across the 2Ω resistor, V = 12V
Resistance, R =2Ω
V = IR
(12) = I(2)
I = 12/2 = 6A
b.
The current flows through the resistor
= the reading of the ammeter
= 6Ω
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For the circuit above,
- find the reading of the ammeter.
- find the current flows through each of the resistors.
Answer:
a.
Potential difference across the 2 resistors, V = 12V
The equivalent resistance of the 2 resistors, R =6Ω
V = IR
(12) = I(6)
I = 12/6 = 2A
The current flows through the resistors
= the reading of the ammeter
= 2Ω
Finding Current in a Parallel Circuit
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In parallel circuit, the potential difference (V) across each of the resistors is equal to the e.m.f. (E) if the internal resistance of the cell is ignored.
By Ohm’s Law
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For the diagram above,
a. find the reading of the ammeter.
b. find the current in each of the resistors.
Answer:
a.
Effective resistance of the 2 resistors in parallel
Potential difference across the 2 resistance, V = 3V
V = IR
(3) = I(2)
I = 3/2 = 1.5A
Reading of the ammeter = 1.5A
b.
Current in the 3Ω resistor,
V = IR
(3) = I(3)
I = 3/3 = 1A
Current in the 6Ω resistor,
V = IR
(3) = I(6)
I = 3/6 = 0.5A
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Figure above shows 3 identical resistors connected in parallel in a circuit. Given that the resistance of the resistors are 6Ω each. Find the reading of all the ammeters in the figure above.
Answer:
The potential diffrence across the resistors V = 6V
For ammeter A,
The equivalent resistance = 6/3 = 2Ω.
V = IR
(6) = I(2)
I = 6/2 = 3A
For ammeter A1,
V = IR
(6) = I(6)
I = 6/6 = 1A
For ammeter A2,
(6) = I(6)
I = 6/6 = 1A
Finding Potential Difference in a Series Circuit
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In the circuit above, if the current in the circuit is I, then the potential difference across each of the resistor is
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Find the potential difference across each of the resistors in the diagram above.
Answer:
The potential difference across the 2 resistors, V = 12V
The equivalent resistance of the 2 resistors, R = 2 + 4 = 6Ω
Current pass through the 2 resistor,
For resistor R1,
V = IR
V = (2)(2) = 4V
For resistor R2
V = IR
V = (2)(4) = 8V