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# Resistance Based Physics Problems

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1. You've made the finals of the Science Olympics! As one of your tasks, you're given 2.0g of copper and asked to make a cylindrical wire, using all the metal, with a resistance of 2.0omega .

a) What length (l) will you choose for your wire?

b) What diameter (d) will you choose for your wire?

2. The relatively high resistivity of dry skin, about 1×10^6 omega⋅m, can safely limit the flow of current into deeper tissues of the body. Suppose an electrical worker places his palm on an instrument whose metal case is accidently connected to a high voltage. The skin of the palm is about 1.5 mm thick.

a) Assume the area of skin on the worker's palm that would contact a flat panel is 1.3×10^−2 m^2 , then calculate the approximate resistance of the skin of the palm.
Express your answer to two significant figures and include the appropriate units.

https://brainmass.com/physics/electricity-magnetism/resistance-based-physics-problems-572112

#### Solution Preview

1. mass of copper, m = 2.0 g = 2.0*10^(-3) kg
resistance, R = 2.0 ohm

density of copper, D = 8.96*10^3 kg/m^3

Hence, volume, V = m/D = 2.0*10^(-3)/(8.96*10^3) m^3

Resistivity of copper, rho = 16.78*10^(-9) ohm.m

Let us assume, length = L and cross-sectional area = ...

#### Solution Summary

Two problems of relation among resistance, resistivity, length and cross-sectional area are solved. All calculations are included.

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