Consider two copper wires with circular cross-sections and equal lengths. One wi

Question

Consider two copper wires with circular cross-sections and equal lengths. One wire has 3 times the diameter of the other. How do the resistances of these two wires compare?

A) The thicker wire has 1/3 the resistance of the thinner wire.

B) The thicker wire has 1/9 the resistance of the thinner wire.

C) The thicker wire has 3 times the resistance of the thinner wire.

D) The thicker wire has 9 times the resistance of the thinner wire.

E) The thicker wire has times the resistance of the thinner wire.

Explanation / Answer

R = p*l / A

p= resistivity

l= length, A = area = pi*d^2/4

so R is inversely proportional to area

so R1/ R2 = A2/A1 = (3D)^2/ (D)^2

=> R2 = R1 / 9

so answer is B

Related Questions

Navigate

• Browse (All)
• Browse C
• Subjects