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Doubly ionized helium ions are projected...

Doubly ionized helium ions are projected with a speed of `10kms^(-1)` in a direction perpendicular to a uniformmagnetic field of magnitude 1.0 T. Find (a) the force acting on an ion, (b) the radius of the circle in which it ciruclates and ( c) the time taken by an ion to complete the circle.

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` V = 10^(4) m/s , B = 1.0 T , q = 2C `
(a) F= qVB `
`= 2 xx 1.6 xx 10 ^(-10) xx 10 ^(4) xx 1.6 `
` = 3.2 xx 10 ^(-10) N `
` (b ) r = (mV)/(qB) =(2 xx 10 ^(-20) ) /(10^(-10) ) `
` = 2 xx 10 ^(-4) m`
` T = (2 pi r ) /(V) = (628 xx 21 xx 10^(-4))/(10^(4))`
`= 1.31 xx 10^(-7) S`.
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