Answer to Question 1

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Use I = nAve

For copper:

Work out the area:

   A = (p (1.4 10-3 m)2) 4 = 1.54 10-6 m2

   v = 0.52 A (8.0 1028 m-3 1.54 10-6 m2 1.6 10-19 C) = 2.64 10-5 m s-1 (= 0.026 mm/s)

 

For Tungsten:

Work out the area:

   A = (p (0.020 10-3 m)2) 4 = 3.14 10-10 m2

   v = 0.52 A (3.4 1028 m-3 3.14 10-10 m2 1.6 10-19 C) = 0.304 m s-1 (= 300 mm/s)