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Homework Statement
Some lightdimmer switches use a variable resistor as shown in figure. The slide moves from position x = 0 to x = 1, and the resistance up to slide position x is proportional to x (the total resistance is R_{pot} = 100Ω at x = 1). What is the power expended in the light bulb if x = 0.5?
Homework Equations
R_{series} = R_{1} + R_{2} + ...
R_{parallel} = 1 / (1 / R_{1} + 1 / R_{2} + ...)
P = V^{2} / R = I^{2}R
The Attempt at a Solution
I tried first to obtain the total resistance, which is 50 + 1 / (1 / 50 + 1 / 205), and use this number to divide the voltage squared in order to get the power, but this is not correct. I don't know what I'm missing here. Any help will be appreciated.
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