Given: The power absorbed by the 15 ohm resistor is 15 W. Find R.
parallel circuit for 2 resistor: Req =R1R2/ R1+R2
Voltage Division Rule: for series circuit VR2 = VsR2/(R1+R2)
The Attempt at a Solution
P = V2/R
P = 15W, R = 15Ω
P at 15Ω = 15 W => V at 15Ω = 15V
=> V at R = 25V - 15V = 10V
So I go around the circuit from the left to right.
Start at the double 4Ω => Req = 2Ω
the 2Ω + 6Ω || 24Ω => Req = 6Ω
6Ω+4Ω || 15Ω => Req = 6Ω
now the circuit only have R and the 6Ω
apply VR2 = VsR2/(R1+R2)
Plug in the number
solve for R = 4Ω
Please let me know if this is the right approach or if I have made a mistake.
Thanks for your time.
Last edited by a moderator: