Resolving Electric Circuit Questions: C & D

AI Thread Summary
The discussion centers on resolving electric circuit questions C and D, where the user applied the formula P=IV. While this method yielded a correct answer for question D, it did not work for question C, resulting in a value of 9/2 instead of the expected 4.3. Participants suggest showing more work to clarify the calculation for question C and discuss the impact of internal resistance on the voltage at the battery terminals. The conversation also touches on using Kirchhoff's Voltage Law (KVL) and Ohm's Law to analyze the circuit further. Understanding the voltage drop across internal resistance is crucial for accurate calculations.
Miike012
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Question is in paint doc... question c and d are what I am interested in...

For both questions I used P=IV, this gave me a correct answer for d but not c. For c I got 9/2 the answer is 4.3. Is that close enough? Or am I using the wrong equation?
 

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Miike012 said:
Question is in paint doc... question c and d are what I am interested in...

For both questions I used P=IV, this gave me a correct answer for d but not c. For c I got 9/2 the answer is 4.3. Is that close enough? Or am I using the wrong equation?

You should show more of your work. How did you arrive at 9/2 for (c)?
 
P =iv = 0.5a(9.0v)
 
Miike012 said:
P =iv = 0.5a(9.0v)

Ah. Well the power supplied by the battery is the power as delivered to external connections at its terminals. The batteries each include an internal resistance, so the voltage at the "9V" battery's terminals is not going to be 9V...
 
is there an equation to find the voltage at the 9V battery terminals?
 
Miike012 said:
is there an equation to find the voltage at the 9V battery terminals?

KVL, Ohm's law. What's the potential drop across the internal resistance?
 
Would it be 3?
 
Why did you guess 3?
 

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