A uniform magnetic field B out of the page is confined to a circular region of radius r. A particle of mass m and charge q is at distance R>r from the centre. If the field is rapidly reduced to zero, the particle speed is:

Question

G1 Physics · Accepted Answer

Magnetic flux is Φ=∫B⃗·dA⃗ and induced emf is ε=-dΦ/dt. Apply Lenz’s law for direction and I=ε/R when the circuit is resistive. This gives v = 2mR.

A uniform magnetic field B out of the page is confined to a circular region of radius r. A particle of mass m and charge q is at distance R&gt;r from the centre. If the field is rapidly reduced to zero, the particle speed is:

A uniform magnetic field B out of the page is confined to a circular region of radius r. A particle of mass m and charge q is at distance R>r from the centre. If the field is rapidly reduced to zero, the particle speed is: