Imagine that you have a box of 9V batteries and a box of flashlight bulbs labeled 1.5V/3W for operational voltage/power. What is the ohmic resistance of the bulbs? Can you turn on the 1.5V bulbs without burning them out by using the available 9V batteries?
I = P/V
R = V/I
The Attempt at a Solution
I in the bulbs will be 3W/1.5V which is 2A
R in the bulbs will be 1.5V/2A which is .75ohms
If you attach one of the bulbs to a 9V battery, the voltage drop will be = to IR which is (2A)(.75ohms) which is 1.5V. So using a 9V battery the bulb will only get 1.5V which will not cause the bulb to burn out. Is this correct?