question: calculate the electric resistance of an iron rod 2.00 m long, assuming that its cross-sectional area is 0.90 square millimeter...
i really dont have an idea on how to solve this.. i badly need your help, so, please help me...
2007-03-23 09:18:27 · 2 answers · asked by mulan 1 in Science & Mathematics ➔ Physics
Resistance is proportional length (L) and inversely proportional A (cross sectional area)
R proportional to L / A
R = rho * L / A
L = 2 m,
A = 0.90 mm^2 = 0.90*(1/1000)^2 = 0.9 * 10^-6 m^2
BUT rho the resistivity of iron is not given in the question
*****************************************************************************on internet (rho)iron = 9.71 * 10^-8 ohm-meter
R = 9.71 * 10^-8 * [ 2 / 0.9 * 10^-6] ohm
R = 21.57 * 10^-2 ohm
2007-03-23 10:11:57 · answer #1 · answered by anil bakshi 7 · 0⤊ 0⤋
The equation is R = (L/A)*Ï where Ï is the resistivity of iron. (See the reference)
You have L & A, and Ï = 1E-7 for iron.
Plug in the numbers, but remember to convert mm² to meter²...
2007-03-23 17:20:58 · answer #2 · answered by Steve 7 · 0⤊ 0⤋