# Location of high and low potential points in motional emf Okay so in the above image the semi circular loop is rotated and a sector of it is introduced into the magnetic field.

Questions:

1. I know the magnetic field is constant so no non conservative electric fields will be induced in the loop. Therefore, the charges must accumulate somewhere and create difference in potentials. Where will the high and low potential points be?

2. Emf is only induced when the area of a current carrying loop increases. In the above figure the part of loop inside the current carrying wire is not a complete circuit (The two vertical lines are not wires). Why is an emf induced?

• You have to show some own effort first. Hint: (motion + magnetic field) - induced force on mobile charge carriers (electrons) in some wire element per unit charge is $\mathbf v \times \mathbf B$ where $\mathbf v$ is velocity of the wire element. This means there is force driving the current only in part of the circuit. Try to identify which one. Jun 6, 2021 at 23:27
• I doubt there will be accumulation of charge, because the circuit is closed and there is nothing to prevent redistribution in the part of the circuit where no EMF is present. Maybe the assignment is wrong? Jun 6, 2021 at 23:33

Also, this EMF is a non-conservative electric field, as $$\oint E.dl = \frac{\partial}{\partial t}\iint B.dS \neq 0$$ for the loop.