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.

 

 

Answer 1

(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