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

Home

Electricity

Circuits

Examples

Resistance of a lightbulb

Index

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= DV / R

= 0.9 V/W

= 0.9 V/(V/A)

= 0.9 A

Last Update: 2006-Nov-21