A. 3.33 A
B. 8 A
C. 10 A
D. 13.32 A
THIS IS THE WHOLE QUESTION
A complete circuit contains two parallel connected devices and the generator for providing the electronmotive force the resistance of the first device is 12 ohms the resistance of the second device is 4 ohms and the voltage developed by the generator is 40V what is the magnitude of the current flowing through the first device?
The question is written as to contain a constant voltage source. Because the 2 devices are connected in parallel, the voltage drop across both will be 40 v, like Bill said. 40v/12 ohms gives you the answer you are looking for.
Had the devices been in series, you would have had what is known as a voltage divider and the current through both devices would have been the same.
I=E/R. You can calculate the resistance of the two devices in parallel, or just add the currents.