Calculating Heat Loss in a Series Circuit

AI Thread Summary
To calculate heat loss in a series circuit with two batteries (12V and 6V) and two resistors (6 ohms and 4 ohms), the correct approach involves determining the total voltage and resistance, as well as the current flowing through the circuit. The initial calculation using P = V^2/R was incorrect due to misapplication of the formula for series circuits. Instead, using P = I^2Rt or applying Kirchhoff's Voltage Law (KVL) is recommended to find the correct values. A circuit diagram and proper calculations for loop current are essential for accurate results. Understanding the relationship between voltage, current, and resistance is crucial for solving heat loss in this context.
Renue
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Homework Statement


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).

Homework Equations

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.
 
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What is the total voltage change across the batteries? What is the total resistance of the resistors? What is the current?
 
Renue said:
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.

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

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