Go Back   Physics Help Forum > College/University Physics Help > Advanced Electricity and Magnetism

Advanced Electricity and Magnetism Advanced Electricity and Magnetism Physics Help Forum

LinkBack Thread Tools Display Modes
Old May 2nd 2009, 03:21 PM   #1
Junior Member
Join Date: Mar 2009
Posts: 3
Question the effect of change in area of a wire loop...?

A circular loop in the plane of the paper lies in a .75 T magnetic field pointing into the paper. If the loops diameter changes from 20.0 cm to 6.0 cm in .50 s, (a) what is the direction of the induced current? (b) what is the magnitude of the average induced emf? (c) if the coil resistence is 2.5 ohms, what is the average induced current?

I though that a changing magnetic field, B, induced current...how does a changing area affect anything except flux..?
pinkprincess08 is offline   Reply With Quote
Old May 2nd 2009, 07:52 PM   #2
Physics Team
Join Date: Feb 2009
Location: India
Posts: 365
Faraday's Law of electromagnetic induction says that change in magnetic flux causes induced emf and the magnitude of emf is given by change in flux/time.
This flux f is defined as-

f = B.A Where B is the magnetic field intensity and A is the area. If the angle between B and A be @ then

f = BA cos@

So if any one out of B, A and @ changes, emf will be induced. Note, if A changes we call it motional emf. Change of @ is used in generators where a coil is rotated in the magnetic field.

Let diameter changes from d to d' in time t then magnitude of

induced emf = change in flux divided by time
= {II(d/2)^2*B - II(d'/2)^2*B}/t
Parvez is offline   Reply With Quote

  Physics Help Forum > College/University Physics Help > Advanced Electricity and Magnetism

area, change, effect, electromagnetic induction, faraday's law, loop, magnetic fields, wire

Search tags for this page
Click on a term to search for related topics.
Thread Tools
Display Modes

Similar Physics Forum Discussions
Thread Thread Starter Forum Replies Last Post
Is EMF generated in this special loop of wire fogo57 Advanced Electricity and Magnetism 2 Oct 16th 2012 05:06 AM
What is the specification of the rebar tie wire and loop wire ties? bearfrods Electricity and Magnetism 0 Feb 26th 2012 10:06 PM
current loop, determine magnitude of force acting on loop. rcmango Electricity and Magnetism 2 Jul 31st 2011 11:22 PM
Induction in a loop of wire AStaunton Electricity and Magnetism 5 Feb 11th 2011 12:13 PM
Change in frequency-Doppler effect jonbrutal Waves and Sound 1 Mar 14th 2009 02:49 AM

Facebook Twitter Google+ RSS Feed