Question

Please write the equation for magnetic force on a particle. For each option please say whether the magnetic field could or could not exert a force on a particle and say why, referencing the magnetic force equation.

a) The particle moves perpendicular to the field.

b) The particle is at rest.

c) The particle is charged.

d) The particle moves parallel to the field.

e) The magnitude of the magnetic field changes with time.

Answer 1

Lorentz force = F = qv*B = qvB sin(theta)

Theta is angle between velocity and magnetic field Direction.

a) if particle move perpendicular to magnetic field then sin(theta) = 1 as theta = 90°. Therefore charge will experience a force on it which is = qvb

b)if V = 0 , force = 0 from Lorentz force equation

c) charged particle will experience force as shown in Lorentz equation if v*B not equal to zero. Uncharged particle will not experience magnetic force in any condition.

d) if particle move parallel to magnetic field then theta will be equal to zero and sin(theta) also equal to zero and Hence force = 0

e) if magnitude of magnetic field changes then also charge can experience force as shown in Lorentz equation if other things satisfy proper condition like charge and velocity should not equal to zero and velocity should not parallel to magnetic field.