A circuit consists of parallel combination 8&12ohms& unknown resistance of R ohm is connected in series with it the total power consume is 70w. When the source voltage is 20V calculate the value of unknown

Answer 1

R1 = 8 Ohms.
R2 = 12 Ohms.
R3 = ?.

20I = 70, I = 3.5A.

Rt = 20V/3.5A = 5.71 Ohms.

Rt = (R1*R2)/(R1+R2) + R3.
Rt = (8*12)/(8+12) + R3 = 5.71.
R3 = ?.