A uniform magnetic field of magnitude 0.20 T exists in space from east to west what speed should a particle of mass 0.010 g and having a charge `1.0 xx 10^(-5)C` be projected from south to north so that it moves with a uniform velocity?

Explanation

`B = 0.2T` ,
`q= 1.0 xx 10^(-5) C`,
`m = 0.01g = 1 xx 10^(-5) kg`
Force dus to magnetic field = Gravitational force of attraction
So , `qVB = mg`
`rArr 1 xx 10^(-5) V xx 10 ^(-1) = 1 xx 10^(-5) xx 9.8`
`V= 4.9 xx 10 = 49m/s `.