You hold a metal ring horizontally above a bar magnet standing on its end. You drop the ring and catch it before it reaches the magnet. When, if ever, is a current induced in the ring?

Only when the ring stops falling

only when the ring starts falling

while the ring is falling

never, current is not induced

never, current is not induced

Explanation:

The induced emf in the ring equals the rate of change of magnetic flux in the ring.

E = -dФ/dt = -dAB/dt = -BdA/dt since B the magnetic field is constant.

E = -BdA/dt

Now dA/dt = dA/dy × dy/dt where dA/dy = rate of change of area with vertical distance as the ring is falling. dy/dt = speed of ring.

Since the ring is falling freely before being caught, its speed v is gotten from v = u + at where u = 0 and a = -g

v = 0 - gt = -gt

v = -gt  

So, dA/dt = dA/dy × dy/dt = vdA/dy = -gtdA/dy

So E = -BdA/dt = -B × -gtdA/dy = BgtdA/dy

Since dA/dy = 0 since the area of the ring does not change with vertical distance. So,

E = BgtdA/dy = Bgt × 0 = 0

E = 0

So, emf is never induced because the flux through the ring remains constant

the answer is mosques. they are an important part of islamic culture.

this is an example of "committed" time.

committed time, as contracted time, takes need over essential and available time since it is seen as profitable work. it alludes to the time allotted to keep up a home and family. at the point when a man is commuting using committed time this individual may feel that the drive is an obligation to family, for example, strolling youngsters to class or driving a mate to work. contracted and committed time clients may feel that their commute could really compare to the commute of important or leisure time clients on the grounds that their commute is profitable work. in this manner, they might be more disposed to pick a mechanized method of movement.