Phy 202 & 214 Quiz 17 February 18, 2008

Three identical long bulbs are in series as shown. The wires.connecting the bulbs have negligible resistance. In the steady state, 3 x 10¹⁷ electrons leave the battery at location A every second.

1. How many electrons enter the second bulb at location D every second? If there is insufficient information to give a numerical answer, state how it compares with 3x10¹⁷. Justify your answer carefully.

2. Next the middle bulb (at DE) is replaced by a wire:

Now how many electrons leave the batteries at location A every second? Explain clearly! If you have to make an approximation, state what it is. Remember not to use voltage or potential or ohms or series-resistance formulas in your explanation, unless you can show in detail how these concepts follow from the more fundamental concepts of charge, field, and energy.