Question

3. The resistance of a silver wire can be calculated by the following formula: Resistance (in Ω) = p x l/A Where p is the resistivity of the material at room temperature (20°C). l is the length of the wire in feet, and A is the cross section area of the wire in CM. If the resistivity of the silver wire is 1.59x10^-8Ωm, what will be the cross section area of the wire. A, if its resistance is 100Ω and the length of wire is 800 m?

Answer 1

R = p L/A

For silver p = 1.59 x 10^-8 ohms-meter

A = ? when R = 100 ohms and L = 800m

R = p L/A

In this case:

100 = (1.59 x 10^-8) (800)/A

Solving for A:

A = (1.59 x 10^-8) (800)/100 = (1.59 x 10^-8)(8) = 12.72 x 10^-8 = 1.272 x 10 ^-7

A = = 1.272 x 10 ^-7

Answer:

A = 1.272 x 10 ^-7 square meters