A wire 5.38 m long and 7.34 mm in diameter has a resistance of 21.7 m. A potenti
ID: 1978773 • Letter: A
Question
A wire 5.38 m long and 7.34 mm in diameter has a resistance of 21.7 m. A potential difference of 17.9 V is applied between the ends. (a) What is the current in amperes in the wire? (b) What is the magnitude of the current density? (c) Calculate the resistivity of the material of which the wire is made.
(a)
Number
Units
(b)
Number
Units
(c)
Number
Units
Chapter 26, Problem 18A wire 5.38 m long and 7.34 mm in diameter has a resistance of 21.7 m. A potential difference of 17.9 V is applied between the ends. (a) What is the current in amperes in the wire? (b) What is the magnitude of the current density? (c) Calculate the resistivity of the material of which the wire is made.
(a)
Number
Units
(b)
Number
Units
(c)
Number
Units
Explanation / Answer
a). current = V/R = 17.9/(21.7m ohm) = 824.88 A b).current density J = i/surface area = 824.88 /(pi * (diameter/2)^2) = 824.88 / (4.23 * 10 ^-5) = 19.49 * 10^6 A /m^2 c).resistivity = R * A / l = 21.7 * 4.23 * 10 ^-5 / 5.38 = 1.7 * 10^-4 ohm-metre
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