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Unformatted text preview: V=1.4v d=0.84 mm D=52.7 mm c. Data analysis: According to the Ohm’s law, we know V = I ∗ R . In this part, specifically V = I ( R + R A ) . Consider the rheostat is a wire resistor rolled in to a cylinder. And we know R = ρL A . Therefore, substitute into equation V = I ( ρπDN A + R A ) , where D is the diameter of the cylinder, N is the turn on the cylinder, and A is the area of the wire. Change the equation little bit 1 I = πρD AV ∗ N + R A V . This equation suit the graph we got. Consider 1 I as y, and N as x. Then πρD AV would be the slope. D is 0.0527m, and slope of the line is 8.360. Therefore, we can find the ρ is 41 ∗ 10 − 8 . Comparing this number to the resistivity table, it is close to manganin alloy’s resistivity 48 ∗ 10 − 8 . So we can say the material in rheostat is manganin alloy. d. Conclusion: the material used in the rheostat is manganin alloy. e. Calculation....
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 Fall '09
 PAULA
 Physics, Current, Resistor, Electrical resistance, Rheostat, DCR Lab Report, resistor. Different materials, equation little bit

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