Answer to Question #309155 in Physics for Sally

Question

SHOW SOLUTION:

1. Compute the resistance of a conductor given a resistivity of 10.4Ωm, length of 4m, and a diameter of 20mm.

2. A length of a gold wire (α = 3.4 x 10^

-3) has a resistance of 10 ohms at 25 degrees Celsius. Calculate resistance if the temperature rises to 90 degrees Celsius.

Answer 1

1.

$$R=\rho\frac{l}{A}=10.4*\frac{4}{3.14*0.01^2}=1.32*10^5\:\Omega$$

2.

$$R(t_2)=R(t_1)(1+\alpha(t_2-t_1))\\ =10*(1+3.4*10^{-3}*(90-25))=12\:\Omega$$