A solid cube of silver (density = 10.5 g/cm3) has a mass of 90.0 g. What is the resistance between opposite faces of the cube?
The solid cube of silver, between the opposite faces of which we have to find the resistance, has a density of 10.5 g/cm^3 and a mass of 90 g.
Now density is given by mass/ volume or volume is equal to mass/ density.
Here, the volume is equal to 90/ 10.5 cm^3.
The volume of a cube with sides of length l is equal to l^3
=> l^3 = 90/ 10.5
=> l = (90/10.5) ^ (1/3) cm
=> l = 2.04 cm
=> l = .0204 m
The resistivity of silver is 15.87* 10^-9 ohm*m.
So the resistance between opposite faces of the cube is: 0.0204*15.87*10^-9
The required resistance between the opposite faces of the silver cube is 0.317*10^-9 ohm.
like justaguide said, I = 0.0204
However, the unit of the resistance he found is expressed in ohm.m^2, which is wrong. it should be ohm.
So I thing all you should do is devise the answer he found by the cross sectional area of the cube, which is I^2.
once again, i not sure of my answer because I found your question by googling it, because I wanted the answer too :D but one thing is sure: Justaguide's answer isn't logic :S