A 12 V battery drives 3 A through a resistor. The resistance is:

## **The reasoning** This is a straightforward application of **Ohm's Law**: V = IR You're given: - Voltage (V) = 12 V - Current (I) = 3 A - Resistance (R) = ? Rearrange the formula to solve for R: R = V/I = 12 V ÷ 3 A = **4 Ω** That's it! Ohm's Law is your best friend in circuits. Whenever you know any two of V, I, or R, you can always find the third. ## **Why the wrong options tempt you** - **A) 2 Ω** — You might accidentally subtract (12 - 3 = 9... wait, that's not even here), or divide the wrong way (3 ÷ 12 = 0.25... nope). - **C) 9 Ω** — This trap comes from subtracting instead of dividing (12 - 3 = 9). Wrong operation! - **D) 36 Ω** — You multiplied instead of divided (12 × 3 = 36). Remember: resistance **opposes** current, so it should be V divided by I, not multiplied. ## **Quick takeaway** **"Resistance = Voltage ÷ Current"** — just remember V = IR, and you'll handle any Ohm's Law question with confidence!