Download Motional EMF

Kiran shakoor
Roll no 07-05
BS(IT)3rd
Motional EMF:
 The emf induced by the motion of a
conductor across a magnetic field is called
motional emf
 When a conductor is moved across a
magnetic field an emf is induced between
its ends.the emf of the moving conductor is
similar to that of a battery
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 Consider a length l of
conductor moving to the
right in a magnetic field
that is into the diagram.
Positive charges in the
conductor will experience
an upward force and
negative charges a
downward force
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DIRECTION OF FORCE
VELOCITY AND FIELD
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 The net result is that
charges will “pile up”
at the two ends of the
conductor and create
an electric field E
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 When the force
produced by E
becomes large enough
to balance the
magnetic force, the
movement of charges
will stop and the
system will be in
equilibrium.
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 When the conductor moves it acts as source
ε
of emf The motional emf will equal to
the potential difference b/w the two ends of
conductor in this equilibrium state
ε = ∆V
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The magnetic force will be
FB=qvB
The electric force will be
FE=qE
Since both are equal
FB=FE
so
qvB=qE
Both q will cancel each other
E=vB
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E=-ΔV/L
ΔV=-LE
E=vB
The motional emf is
The magnitude is
ε=ΔV=-LvB
ε= LvB
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