In the circuit shown below :
The potential difference across the 3 Ω resistor is:
Here all the resistance are connected in series. Therefore net resistance = 2Ω+3Ω+1Ω =6Ω
So current in the circuit = 
Potential across 3Ω resistor 
39
In the circuit shown below :
The potential difference across the 3 Ω resistor is:
Here all the resistance are connected in series. Therefore net resistance = 2Ω+3Ω+1Ω =6Ω
So current in the circuit =
Potential across 3Ω resistor