🔍 Key Concepts

• Parallel vs. series resistance – how to find the equivalent resistance of R1 and R2 when they are in parallel • Ohm’s Law: ( I = \frac{E}{R} ) and power formulas: ( P = EI = I^2R = \frac{E^2}{R} ) • How voltage behaves in a series–parallel circuit (same voltage across parallel branches, current divides)

💭 Think About

• First, focus only on the section that is clearly in parallel in figure B. Which resistors share the same two connection points with each other? • Once you have the equivalent resistance of that parallel pair, what is the voltage across that pair, considering there is another resistor in series (R3)? • After you know the voltage across the parallel section, which power formula is easiest to apply to that part of the circuit alone?

✅ Before You Answer

• Be sure you correctly compute the equivalent resistance of R1 and R2 in parallel using ( R_{eq} = \left( \frac{1}{R_1} + \frac{1}{R_2} \right)^{-1} ) • Confirm what portion of the 30 V source actually appears across the parallel combination (you may need to find total circuit resistance first). • After finding power, check if your value is reasonable compared to the total power from the source (it cannot exceed total power and should be a significant fraction of it).