Question

Resistor of 5 ohm is parallel with an unknown resistor of R1 ohm .This combination is connected in series with an unknown resistor of R2 ohm and the complete circuit is then connected to 50V dc supply. Calculate the values of R1 and R2, if the power dissipated by the unknown resistor is 150W with 5A passing through it. ​

Answer 1

Answer:

R1=6Ω. R2=20/11Ω

Explanation:

power P=R*I^2

R = 150/(5*5) =6Ω

considering this is the condition given for R1.

Now R1 and 5Ω are in parallel. Therefore current through 5Ω is i, where 5*i = 6*5.

Hence current through 5Ω is 6A.

Now voltage drop across the parallel combination is 5*6=30V. Therefore voltage drop across R2 is 50-30=20V.

Current through the parallel combination is 5A+6A =11A, this flows through the R2.

Now 20V=R2*11.

R2=20/11Ω