Question

A certain wire has resistance R, another wire of the same material ,has half the length andhalf the diameter of first wire.. The resistance of second wire is...
a.R/4
b.R/2
c.2R
d.R​

Answer 1

Answer:

a) R/4 is the correct answer.

Answer 2

Answer:

answer is 2R

Explanation:

The resistance of the second wire is approximately twice that of the first wire.

Resistance and length are directly proportional. Resistance and size are inversely proportional.

To determine the resistance of a conductor I used the following formula:

R= K x L / Area

K= constant (for copper I used 10.4)

L= length in feet

Area= size of the conductor expressed in circular mils

Using the Table 8 in the NEC Conductor Properties:

#14 is approximately 1/2 the diameter as #8

#14—area is 4110 circular mils

#8—area is 16,510 circular mils

So, plugging those numbers into the formula:

#14: R= 10.4 x 500’/ 4110= 1.265 ohms

#8: R= 10.4 x 1000’/ 16,510= 0.6299 ohms