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a proton moving with a speed of 1.0 x 106ms-...

a proton moving with a speed of 1.0 x 106ms-1 through a magnetic field of 1.0T experiences a magnetic force of magnitude 8.0 x 10-14 N. The angle between the proton's velocity and the field is

A.

60°

B.

90°

C.

30°

D.

45°

Correct answer is C

The force acting on moving charge in magnetic field is given by: F=q VBSin θ
sin θ =F=(8.0x10)-14/1.6x10-19x1.0x106x1.0 = (8.0x10)14/16 x 1013
(8.0x 10)-14/16x10-14
=0.5000
∴ θ= sin-1 0.5000
=30°