A magnetic field B is confined to a region r ≤ a and points out of the paper (the z-axis), r = 0 being the center of the circular region. A charged ring (charge = Q) of radius b, b >a and mass m lies in the x-y plane with its center at the origin. The ring is free to rotate and is at rest. The magnetic field is brought to zero in time Δt. Find the angular velocity of the ring after the field vanishes.
if E is the electric field generated area the charged ring of radius b, then

i.e.,,

torque activity on the ring

if ∆l is charge in the angular momentum if the charge ring then

L₂-4 = T∆t

initial angular momentum L₁ =0

Question

if E is the electric field generated area the charged ring of radius b, then

i.e.,,

torque activity on the ring

if ∆l is charge in the angular momentum if the charge ring then

L₂-4 = T∆t

initial angular momentum L₁ =0

Philoid · Accepted Answer

if E is the electric field generated area the charged ring of radius b, then

i.e.,,

torque activity on the ring

if ∆l is charge in the angular momentum if the charge ring then

L₂-4 = T∆t

initial angular momentum L₁ =0