A tungsten wire has resistance R at 20°C. A second tungsten wire at 20°C has twice the length and half the cross-sectional area

Question

Alexus [3.1K]

3 years ago

8

A tungsten wire has resistance R at 20°C. A second tungsten wire at 20°C has twice the length and half the cross-sectional area

of the first wire. In terms of R, the resistance of the second wire is
(1)R/2
(2)2R
(3)R
(4)4R

Physics

1 answer:

Bad White [126] · Answer 1 · 2022-07-25T16:59:57+03:00

The resistance is 4 times the resistance of the first wire. the formula is R = p*l/A with p being resistivity, l length and A area. So if you double length and half area, which botv result in more resistance, you get p*2/0.5 or 4 (p can be abandoned because it is the same. We take standard length and area as 1)