Which of the following bulbs will have the least resistance?
- A. 220 V, 60 W
- B. 220 V, 100 W
- C. 115 V, 60 W
- D. 115 V, 100 W
Answer: D. 115 V, 100 W
Explanation: $R = \frac{V²}{P}$. \n$R_1 = \frac{220^2}{60} = 806.6~\Omega$. \n$R_2 = \frac{220^2}{100} = 484~\Omega$. \n$R_3 = \frac{115^2}{60} = 220.4~\Omega$. \n$R_4 = \frac{115^2}{100} = 132.25~\Omega$. \nThe bulb with 115 V, 100 W has the least resistance.