Question

The Nile River runs from east to west. Assume the water in the Nile is electrically neutral while still conducting, and that the ions (both positive and negative in equal concentration) are carried with the flow of the water. What would the electric potential of the north side of the river be in comparision to the southern side due to the lorentz force on the ions. Remember that the magnetic field of the earth has northern and southern components.

Answer 1

Question :The Nile River runs from east to west. Assume the water in the Nile is electrically neutral while still conducting, and that the ions (both positive and negative in equal concentration) are carried with the flow of the water. What would the electric potential of the north side of the river be in comparision to the southern side due to the lorentz force on the ions. Remember that the magnetic field of the earth has northern and southern components.

Sol : Given charges flowing in the east to west direction. and earths magnetic field in the north south direction.

Concept to be used is motional EMF .to find out the direction of the induced EMF, Flemings left hand rule can be used.

FLHR states; Stretch the thumb, the forefinger and the central finger in mutually perpendicular directions,. If the thumb indicates the direction of motion of conductor, forefinger represents the magnetic field, then the central finger indicates the direction of the induced current.

According to the given condition , The thumb points east to west, forefinger points north to south, then by rule the central finger points downwards.. This means that, the induced emf is from top to the bottom. therefore the north and south sides of the river are in the same potential. The Potential difference between north and south will be zero.