Lectures on Physics has been derived from Benjamin Crowell's Light and Matter series of free introductory textbooks on physics. See the editorial for more information....

Resistance of a lightbulb

Question: A flashlight bulb powered by a 9-volt battery has a resistance of 10 O. How much current will it draw?

Solution: Solving the definition of resistance for I, we find

I= ΔV / R

= 0.9 V/Ω

= 0.9 V/(V/A)

= 0.9 A

Last Update: 2010-11-11