Question

The electrical resistance of a wire, R, varies directly as its length, L, and inversely as its cross sectional area, A. If the resistance of a wire is 0.08 ohm when the length is 100 ft and its cross-sectional area is 0.05 in^2 , what is the resistance of a wire whose length is 4000 ft with a cross-sectional area of 0.02in^2 ? a) Write the variation equation. (R=k(l/a) b) Determine the value of the quantity indicated.   ​

Answer 1

see below

Explanation:

a R=k(L/A)

Substitute what we know into the equation

.08 = k (100/.05)

.08 = k 2000

Divide each side by 2000

.08/2000 = k

.00004 = k

R=.00004 (L/A)

b R=.00004 (L/A)

We know L = 4000 and A = .02

R=.00004 (4000/.02)

R = 8