7.3.2 Resistance in Series and Parallel Circuit

1. In a series circuit, the effective resistance is equal to the sum of the individual resistance, as shown in the following equation. 
   
   
   
   
2. In a parallel circuit, the effective resistance of the resistors can be calculated fro the following equation. 
   
   
   
   

Example:

Find the equivalent resistance of the connection shown in the diagram above.

Answer:
(a)
R = 2 + 3 + 6 = 11Ω

(b)

(c)

(d)

1. In a series circuit, the more resistors with equal resistance in the circuit, the higher the effective resistance of the circuit.
2. In a parallel circuit, the more resistors with equal resistance in the circuit, the lower the effective resistance of the circuit.

Finding the Resistance of an Individual Resistor

Example

Given that the equivalent resistance of the connection in the figure above is 0.8Ω, find the resistance of the resistor R.

Answer:

Example

Given that the equivalent resistance of the connection in the figure above is 4Ω, find the resistance of the resistor R.

Answer: