Your professor gives you a summer job organizing his lab. On the first day, you

Question

Your professor gives you a summer job organizing his lab. On the first day, you come across three identically shaped cylinders of metal, each having a diameter of 6.31 mm and a length of 5.07 cm. They appear to be made out of different metals, but they are not labelled! They are, however, packaged with a table of the conductivities of several metals. You locate a multimeter and use it to measure the electrical resistance of each cylinder. Using the measured resistances and the table of conductivities, identify the metal that each cylinder is composed of.

*OPTIONS TO CHOOSE FROM ARE IN BLUE*   

Explanation / Answer

From the equation, R = L/A, we can solve for

= L/RA

L/A for all materials is .0507/()(3.155 X 10-3)2 = 1621 m-1

Sample 1)

= (1621)/(46.3 X 10-6) = 3.50 X 107 (m)-1

Sample 1 is Aluminum

Sample 2)

= (1621)/(186 X 10-6) = 8.72 X 106 (m)-1

Sample 2 is Tin

Sample 3)

= (1621)/(28.5 X 10-6) = 5.69 X 107 (m)-1

Sample 3 is Copper

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