A magnetic field B is confined to a region r a ≤ and points out of the paper (the z-axis), r = 0 being the centre 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 centre at the origin. The ring is free to rotate and is at rest. The magnetic field is brought to zero in time ∆t. Find the angular velocity ω of the ring after the field vanishes.

contexto.120

3 years ago

When the magnetic field is lowered in t, the magnetic flux across the conducting ring drops to zero from its maximum.

E2b = induced emf

According to Faraday’s law of emf,

The induced emf is equal to the rate of change of magnetic flux, which is Ba2/t.

Using the equations above, we obtain

E2b = Ba2/t E2b

The electric force that the ring is subjected to is known as QE.