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?  

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justaguide's profile pic

justaguide | College Teacher | (Level 2) Distinguished Educator

Posted on

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

=0.317*10^-9 ohm.

The required resistance between the opposite faces of the silver cube is 0.317*10^-9 ohm.

alomical's profile pic

alomical | Student, Undergraduate | eNotes Newbie

Posted on

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

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