Calculate Battery Energy Delivery Rate for Parallel Circuit

[Ruleski]

Homework Statement

A current I9 = 2 A flows through the 9 ohm resistor. At what rate does the battery deliver energy to the entire circuit?

Homework Equations

There are 3 resistors in the circuit, all wired in parallel. r1=15 ohms, r2=12 ohms, r3=9 ohms

The Attempt at a Solution

 

[rl.bhat]

What is the expression for the equivalent resistance of the parallel combination?

What is the energy dissipation in the resistance?

In the problem I9 and r3 is given. Find the applied voltage across the parallel combination.

 

[Ruleski]

All I know is that resistance is 1/total=1/r1+1/r2+1/r3. I calculated 3.83 ohms

 

[rl.bhat]

All I know is that resistance is 1/total=1/r1+1/r2+1/r3. I calculated 3.83 ohms

In parallel combination voltage across each branch of the resistance is the same.

So V = I9*r3.

Energy dissipation is W = V^2/r.

 

[Ruleski]

Thank You. I was using the wrong equation for the last step