1) A 2.0 mm diameter iron ball is charged to +46 nC. What fraction of its electr

Question

1) A 2.0 mm diameter iron ball is charged to +46 nC. What fraction of its electrons have been removed? The density of iron is 7,870 kg/m3.


2) The magnetic field of the brain has been measured to be approximately 3.1 10-12 T. Although the currents that cause this field are quite complicated, we can get a rough estimate of their size by modeling them as a single circular current loop 19 cm (the width of a typical head) in diameter. What current is needed to produce such a field at the center of the loop?

Explanation / Answer

Magnetic field of the brain = B = 3.1 x10-12 T   single circular current loop with (the width of a typical head) in diameter =  19 cm    d = 19 cm   so, radious = r = 0.095 m Let , I be the current is needed to produce such a field at the center of the loop = ? It is known by the formual for magnetic field at the center of the circualr loop is B = o I / 2r where : o = 4 x10-7 A/m 3.1 x10-12   =  4 x10-7 ( I ) / 2 (0.095 )       3.1 x10-12     = 66.1 (I )                       I = 0.04689 x10-12 A * Please post first question seperately * * Please post first question seperately *

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