PHY 7B Quiz: 7B+Practice+Quiz+_2c+Solutions.pdf
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For this quiz we treat a lightbulb as having a constant resistance. Ignore the fact that the resistance of the bulb changes with temperature: the household voltage in the united states is 120 volts. Assume that this lightbulb is designed for use in a us household. The resistance of this lightbulb does not change when we bring it down under, so the power dissipated by it when it is introduced to a higher voltage will be greater (because p = ( v)2/r). Therefore it will burn brighter: dimmer switch. We wish to make the 100w lightbulb from 1a) shine with only. These are the dials you some- times nd on a lightswitch that allow you to dim the lights. The rate that charge ows into the resistor must equal the rate that it ows out of it (no charge buildup or loss), and that is the rate that it ows into the lightbulb.