Question

Three resistors A, B, and C are connected in series to a 120 volt source. If R_A is = 64 ohms and E_B = 40volts, when the current is 0.5 amp, calculate the resistances R_B and R_C.

Answer 1

The equivalent resistance of the three resistors is the source voltage over the current:

$$R_\text{eq}=R_A+R_B+R_C=E/I=120/0.5=240\Omega.\\ R_B=E_B/I=40/0.5=80\Omega.\\ R_C=R_\text{eq}-R_A-R_B=240-64-80=96\Omega.$$