🔍 Key Concepts
• Ohms Law and how voltage, current, and resistance are related
• The power formula for resistors: relationships among power (P), voltage (V), current (I), and resistance (R)
• What minimum power rating means in terms of actual power dissipated vs. nameplate rating
💭 Think About
• First, express the current through a 20,000-ohm resistor when 500 V is applied across it. Which Ohms Law formula lets you find current from voltage and resistance?
• Once you know either current or have voltage and resistance, choose the power formula that avoids extra steps: do you want to use P = VI, P = I^2R, or P = V^2/R?
• Compare your calculated power to the answer choices. Should the minimum rating be exactly equal to the calculated power or safely above it?
✅ Before You Answer
• Double-check your unit conversions: ohms, volts, and watts must be consistent with each other
• Confirm that you squared the correct value (voltage or current) in the power formula you used
• Make sure the rating you pick is not less than the power you calculated, since the resistor must safely dissipate that amount of power