# Heat loss in a circuit

Tags:
1. Jul 1, 2017

### Renue

1. The problem statement, all variables and given/known data
Determine the heat loss in the circuit that is connected in series with two batteries (12 V and 6V) and two resistors (6ohms and 4 ohms).

2. Relevant equations

3. The attempt at a solution
I used the difference in P = V^2/R, the power dissipated in the circuit, to calculate the heat loss.
Heat energy loss/t = (12^2/6) - (6^2/4) = 15W.
Apparently, I am incorrect; but I don't know the right direction to solve this problem.
Thanks in advance for your guidance/help.

2. Jul 1, 2017

### Staff: Mentor

What is the total voltage change across the batteries? What is the total resistance of the resistors? What is the current?

3. Jul 1, 2017

### Staff: Mentor

How did you decide that there was 12 V across the 6 Ω resistor and 6 V across the 4 Ω resistor? What is the current flowing in the series circuit? Can it be different for different components? Try writing KVL for the loop.

4. Jul 1, 2017

### Brian blake science

See you used the formula , P=V^2/R but as you mentioned the resistors are connected in series. The formula you used was when the resistors are connected in parallel. Thus wrong formula= wrong answer

Now don't just abuse . Say the right formula. I think most of the people would have this ridiculous thought in their mind . Try using the formula -
P=I^2Rt
Hope it helped!

5. Jul 2, 2017

### CWatters

The equation P=V^2/R works just fine for ALL circuits (series or parallel) if you use the correct values for V and R.

See post #3

6. Jul 2, 2017

### phinds

draw a circuit diagram and show your calculations for the loop current and how you arrive at it and derive the power from it

Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted