1 points HRW9 28 P002 My Notes O Ask Your Teachen A particle of mass 10...

Velocity of the particle, v = 21 km/s = (21 x 1000) m/s = 21000 m/s

Now, expression for the magnetic force due to the motion of the particle -

F = q*v*B*sin

Here, the angle between the magnetic field, B and the velocity of the particle, = 90 deg

So, sin = sin90 = 1

So, the above expression becomes -

F = q*v*B*1 = q*v*B

This force is in upward direction and must be balance by the weight of the particle.

Weight of the particle, W = m*g (in the downward direction)

So -

F = W

=> q*v*B = m*g

=> B = (m*g) / (q*v)

Given -

m = 10 g = 10 x 10^-3 kg

q = 65 micro C = 65 x 10^-6 C

g = 9.8 m/s^2

So -

B = (10 x 10^-3 x 9.8) / (65 x 10^-6 x 21000) = 0.0718 T = 7.18 x 10^-2 T (Answer)