Here, the cause of the EMF is the motion of the rod to the right. The induced EMF establishes a current I in anticlockwise direction, so that the FB acting on the rod is to the left. Thus, opposing the motion of the rod in accordance with lenz’s law.
Direction of EMF alternate method:
Current is anticlockwise.
In this case 3 vectors Blv one mutually ⊥ar the EMF induced is maximum.
Verification of conservation of energy:
As the rod is moving on the parallel rails, smoothly ∴ one chemical energy is converted into electrical energy & which is dissipiated as heat is overcome the resistance of the loop.
Rate of change of magnetic flux due to rate of change of area (general case)
In case of a conducting rod moving on a π shaped conductor, only one side of the loop is moving. But now, we are considering the general case where all sides of the loop are moving in different direction with different velocities.
A part of the loop
In a time dt,
If all sides of the loop are moving in different direction, then the induced EMF
This is the general formula for induced EMF due to time varying area of the loop.
If all parts of the loop are moving with uniform translational velocity of in an uniform magnetic field ‘B’, then the loop observes no change in magnetic flux. Passing through it & hence the induced emf is equal to zero.
It is similar to the rigid loop moving in a uniform magnetic field
∴same flux passes through it.