Some light bulbs are designed to operate at three different brightness levels. Locate such a bulb either in your home or residence hall, or in a local store.
a. Unscrew the bulb from the socket and examine the base of the bulb. Sketch carefully the points at which electrical contact can be made with the base of the bulb.
b. Unplug the lamp and examine the socket. How does it make electrical contact with the bulb? (If you do not have such a lamp handy, your local hardware store will have three-way sockets for sale that you can examine.)
c. If you can see inside the bulb, how many filaments can you identify?
d. Develop an explanation for how the bulb can produce three different brightness levels depending upon the switch position.