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Index
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electromagnetic induction
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Chapter 1
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Level 1
level: Level 1
Questions and Answers List
level questions: Level 1
Question
Answer
magnetic flux formula
magnetic flux = B.A
unit for magnetic flux
weber (wb) and it is scalar
a cylindrical bar magnet is rotated about its axis. a wire is connected from the axis and is made to touch the cylindrical surface through a contact. explain current
as there is no change in magnetic flux associated with the circuit, no current is induced in the circuit. the ammeter A shows no deflection
Lenz's law and conservation of energy
the polarity of induced emf is such that it tends to produce a current which opposes the change in magnetic flux that produced it
self inductance formula
L= mu(r).muo.n^2 AL
unit of self inductance
henry
a metal plate is getting heated. it can be because
a current( either A.C. or D.C) is passing through her. it is placed in a time varying magnetic field
when bulk pieces of conductors are subjected to changing magnetic flux, induced currents are produced in them. however, their flow patterns resemble swirling eddies in water, discovered by foucault.
eddy currents
mutual inductance formula
M21=muo.n1.n2.pi.r1^2l
unit of mutual inductance
henry
faraday's law of EMI
when a closed coil is placed in changing magnetic field then electric current is induced in the coil
formula for finding current in a magnetic feild
I=Btw/R
if current is anticlockwise and clockwise explain the poles formed
north pole for anticlockwise and south pole for clockwise
magnetic flux for n turns
phi=nBA
faraday's law given by
micheal faraday in england and josheph henry in USA around 1830
when north pole of magnet is pulled away from the coil then the galvanometer shows deflection in which direction
opposite direction to the direction when magnet is brought closer
conclusion of faraday's experiments
an induced emf is induced in acoil when a magnetic flux through the coil changes with time
peak value of induced emf
e0=NBAW, e depends on time
induced current in the loop
i=e/R depends on time
induced charge
qi= -dQ/R does not depend on time