# Two light bulbs are each connected to a power supply

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5. Two light bulbs are each connected to a power supply, which provides a constant potential difference of 120 V. It is observed that light bulb 2 is much brighter when connected to this power supply than light bulb 1. + 1 2 + 2 + 1 120 V 120 V 120 V These same two lightbulbs are then connected in the circuit at right. What can we say about the brightness of the bulbs now? A. Bulb 1 glows brighter than bulb 2. B. Bulb 2 glows brighter than bulb 1. C. Both bulbs glow with the same brightness. D. Neither bulb lights up at all. E. This is impossible to answer without knowing more information. 6. A certain wire has resistance R . Another wire, of the same material, has half the length and half the diameter of the first wire. The resistance of the second wire is: 7. A certain capacitor has a capacitance of 3.0 μF. While it is charged to 3.0 μC and isolated, the plates are pulled apart so its capacitance becomes 1.0 μF. The work done by the pulling agent is about: Page 3

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PHYS 251 - MT2 Sample 2 8. The equivalent resistance between points 1 and 2 of the circuit shown is: 1 1 1 2 4 2 5 2 1 9. The same potential difference is applied to across two wires. Wire 1 carries twice the current of wire 2. If the resistance of wire 2 is R, what is the resistance of wire 1? A. 2R B. R/2 C. 4R D. R/4 E. R Page 4