Question

An 8.0 Ω resistor and a 4.0 Ω resistor are
connected in series with a battery. The potential difference across the 4.0 Ω resistor is
measured as 9 V.
Find the potential difference across the battery.

Answer 1

R1 = 8 Ohms.
R2 = 4 )hms.
V2 = 9 Volts.

I = V2/R2 = 9/4 = 2.25A
E = V1 + V2.
E = I*R1 + 9
E = 2.25*8 + 9 = 27 Volts.