🔍 Key Concepts

• Ohm's Law relationships between voltage (E), current (I), and resistance (R) • Power formulas in DC circuits (how P relates to E, I, and R) • How to derive power formulas by substituting Ohm's Law into P = E × I

💭 Think About

• Start from the most basic definition of electrical power in a DC circuit. Which two quantities multiplied together give you power? • Using Ohm's Law (E = I × R), try substituting for E or I into the basic power formula. What expression do you get that involves I and R only? • Look at the answer choices and identify which one matches a standard power formula that depends on current and resistance.

✅ Before You Answer

• Confirm you remember that P = E × I is the fundamental DC power relationship. • Use E = I × R and see what power formula that produces when you substitute into P = E × I. • Check the units: power should come out in watts (W). Make sure the units in the formula you choose are consistent with watts.