A ball with a mass of 100 g which contains 3.60×10 8 excess electrons is dropped

Question

A ball with a mass of 100 g which contains 3.60×108 excess electrons is dropped into a vertical shaft with a height of 105 m . At the bottom of the shaft, the ball suddenly enters a uniform horizontal magnetic field that has a magnitude of 0.290 T and direction from east to west.

Part A

If air resistance is negligibly small, find the magnitude of the force that this magnetic field exerts on the ball just as it enters the field.

Use 1.602×1019 C for the magnitude of the charge on an electron.

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A ball with a mass of 100 g which contains 3.60×108 excess electrons is dropped into a vertical shaft with a height of 105 m . At the bottom of the shaft, the ball suddenly enters a uniform horizontal magnetic field that has a magnitude of 0.290 T and direction from east to west.

Part A

If air resistance is negligibly small, find the magnitude of the force that this magnetic field exerts on the ball just as it enters the field.

Use 1.602×1019 C for the magnitude of the charge on an electron.

SubmitMy AnswersGive Up

Explanation / Answer

F = qvb sin theta

theta = 90 degree

sin90 =1

F = qvB

q = charge due to excess electron = N*q

q = 3.6 x 10^8 * 1.602 x 10^-19 = 5.7672 x 10^-11 C

apply energy conservation

1/2*mv^2 = mgh

v = sqrt(2gh) = sqrt(2*9.8*105)

v = 45.365 m/s

B = 0.290 T

F = qvB

F = 7.587 x 10^-10 N

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