Electric Circuits - Mission EC7 Detailed Help

A 12-V battery is connected to three resistors that have resistance values of 3 ohms, 4 ohms and 5 ohms as shown below. The equivalent resistance of the circuit is ____.


 
Definition of Equivalent Resistance:
The equivalent resistance of a circuit is the amount of resistance that a single resistor would need in order to equal the overall effect of the collection of resistors that are present in the circuit.


 
For series circuits, the mathematical formula for computing the equivalent resistance (Req) from the resistance values of the individual resistors (R1, R2, R3, ...) is:
Req= R1+ R2+ R3+ ...