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Question
The circuit diagram given below shows the combination of three resistors R1, R2 and R3:
Find :
(i) total resistance of the circuit.
(ii) total current flowing in the circuit.
(iii) the potential difference across R1.
Solution
(i) As shown in the figure, the resistors R2 and R3 are connected in parallel. Their total resistance is given by:
1/R = 1/R2+ 1/R3
Here, R2 = 3 Ω
R3 = 6 Ω
So,
1/R = 1/3 + 1/6
Or 1/R = (2+1)/6
1/R = 3/6
R = 2 Ω
This resistance is in series with the resistor, R1.
Total resistance = 2 Ω + R1
R1 = 4 Ω
Therefore, total resistance = 2 Ω + 4 Ω = 6 Ω
(ii) The current through the circuit can be calculated as follows:
Current, I = V / R
I = (12 / 6) A
I = 2 A
(iii) The potential difference across R1 = 2 A x 4 Ω = 8 V
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