Phy 214 Quiz 14 February 11, 2008

1. A single wire across the top of the compass causes a deflection of 30° in needle. If it is now curved back under the compass lined up with the wire on top, the needle will now have:

a. No deflection at all.

b. Only slightly less deflection.

c. Only slightly more deflection.

d. Same deflection in the opposite direction.

e. Twice the deflection in the same direction.

1 alt for 5 pts bonus!!

HW6-2 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.

(b) 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.

2. Given the following three demonstrations, assuming all the filiments are made of the same material, rank the bulbs in terms of diameter of filiments.