0

Guest

Courses New

Define motional emf and derive an expression for it.

Define motional emf and derive an expression for it.

Grade:Upto college level

4 Answers

Apoorva Arora IIT Roorkee
askIITians Faculty 181 Points
9 years ago
When a conductor is moved across a magnetic field, a potential difference is setup across its ends.
This potential difference is called'motional EMF'.
Consider a wire of length "L" moving across the magnetic field of inductionBwith a velocityvas shown in diagram.
237-2343_emf.jpg
Each free electron of the wire is moving within the wire and experience a force exerted by magnetic field.
F=q(v\times B)
here q=-e
F=-e(v\times B)
F=e(B\times v)
These electrons gradually accumulate at the end "a" and leaving the other end "b".In this way point "b" acquires positive charge and point "a" acquires equal negative charge.
This accumulation of electrons will continue till the force of electric field balances the force due to the motion of wire. Thus a potential difference is setup form pointbto pointa.
We know
Potential Difference = work done per unit charge
Let the total charge flows through the wire is "q" therefore
P.D.=work/charge
P.D.=F.d/q
P.D.=e(B\times v)L/e
P.D.=L(B\times v)
or
P.D.=BvLsin\theta
This is called motional EMF.
Thanks and Regards
Apoorva Arora
IIT Roorkee
askIITians Faculty
NIKHIL
15 Points
5 years ago
dfi=B.dA
     =B.I.V.dt
=> €= -dfi/dt
Therefore, €= -BIV
This emf is called motional emf.
Direction of induced current by Fleming's Right Hand Rule.
Aditya
13 Points
5 years ago
Consider a  rod moving in a magnetic field with a velocity v. We know that the rod is containing some free electrons which drift in the rod  towards an end due to magnetic force leading to charge seperated in the rod. Now we can see q(v×B)=qE hence we obtain expression for the induced electric field E = Bv now we now total emf developed in the rod  \int_{0}^{L}(E.dx) = BvL
ankit singh
askIITians Faculty 614 Points
3 years ago
Motional emf: When an conducting loop or rod moves in the in an uniform magnetic field, so that flux through the loop changes, due to the change in the flux through the loop, an emf is induced it the loop, which is called motional emf.

Think You Can Provide A Better Answer ?

Other Related Questions on General Physics

View all Questions »

ASK QUESTION

Get your questions answered by the expert for free

Answer and earn gift vouchers

Win Gift vouchers upto Rs 500/-

View courses by askIITians

Design classes One-on-One in your own way with Top IITians/Medical Professionals

Click Here Know More

Complete Self Study Package designed by Industry Leading Experts

Click Here Know More

Live 1-1 coding classes to unleash the Creator in your Child

Click Here Know More

a Complete All-in-One Study package Fully Loaded inside a Tablet!

Click Here Know More