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Classical Electron Spin Part A If you treat an electron as a classical spherical

ID: 1455344 • Letter: C

Question

Classical Electron Spin

Part A

If you treat an electron as a classical spherical object with radius 1.50×1017 m , what angular speed is necessary to produce a spin angular momentum of magnitude 3/4? Use h = 6.63×1034 Js for Planck's constant, recalling that =h/2, and 9.11×1031 kg for the mass of an electron.

Express your answer in radians per second to three significant figures.

Part B

Use the equation v=r relating velocity to radius and angular velocity together with the result of Part A to calculate the speed v of a point at the electron's equator.

Express your answer in meters per second to three significant figures.

= rad/s  

Explanation / Answer

angular momentum L= I*w

where I = moment of interia = (2/5)mr2

angular velocity w = L/I

= (3/4)*(h/2)0.5 / (2/5)mr2

= 0.75 x (6.63 x 10-34 / 2 x 3.14)0.5 / 0.4 x 9.1 x 10-31 x (1.50 x 10-17)2 rad-s-1

= 9.41 x 1044 rad-s-1   ...................ans

now v=rw

speedv of a point at the electron,s equator v = 1.50 x 10-17 x 9.41 x 1044 ms-1

= 1.41 x 1028 ms-1 ...............ans