Question

Derive an expression for motional emf from the consideration of lorentz force.

Answer 1

Explanation:

When a rod moving in Magnetic field then at that time :

Velocity , Magnetic field , and length of conductor ( rod ) mutually perpendicular to each other..........

The magnetic force = e V B sin@

@ = 90°

The magnetic force = e V B.....( i )

The Electric force ( Fe ) on electron of conductor = q E.....( ii )

When both force are at equilibrium then:

Magnetic force ( Fm ) = Electric force ( Fe )

| Fm | = | Fe |

Putting the value of both force then we get

e V B = e E

E = V B ........ (iii )

We know that :

∆V = E × L

where : ∆V is potential difference

E is Electric field

L is the length of contracted

E = ∆V / L

Putting the value of E in equation ( iii )

Then we get :

( ∆V / L ) = V B

∆V = V B L. or. e = V B L

Thank you