1. With this definition of the flux being , we can now return to Faraday's
investigations. He found that the magnitude of the emf produced depends on the
rate at which the magnetic flux changes. Faraday found that if the flux through
N loops of wire changes by an amount , during a time delta t, the average
induced emf during this time is
This fundamental result is known as Faraday's law of induction.
The minus sign is placed there to remind us in which direction the
induced emf acts. Experiment shows that an induced emf always gives rise to a
current whose magnetic field opposes the original change in flux. This is known
a Lenz's law. Let us apply it to the case of relative motion between a magnet
and a coil. The changing flux induces an emf, which produces a current in the
coil; and this induced current produces its own magnet field. If the distance
between the coil and the magnet decreases; so the magnetic field, and therefore
the flux, through the coil increases. The magnetic field of the magnet points
upward. To oppose this upward increase, the field produced by the induced
current must point downward. Thus Lenz's law tells us that the current must move
by the use of the use of the right hand rule. If the flux decreases, so the
induced current produces an upward magnetic field that is "trying" to maintain
the status quo.
Let us consider what would happen if Lenz's law were just the reverse.
The induced current would produce a flux in the same direction as the original
change; this greater change in flux would produce an even larger current,
followed by a still larger change in flux, and so on. The current would continue
to grow indefinitely, producing power (=) even after the original stimulus ended.
This would violate the conservation of energy. Such "perpetual - motion" devices
...
What Effect will the have on Society? People talk about the , but few actually know what it is and how big an effect is could have. Virtually everything is our society is vulnerable, from water and electricity to our phone bills and savings accounts. The is a design fault dating back to the early days of computers and the way they store time and...
PROJECTILE MOTION * The motion of the body thrown horizontally or an angle other than 90[0] with the horizontal component * Trajectory is the path that a projectile follows * Parabola is the trajectory of a projectile * Two components of projectile motion: Vertical component- air resistance is neglected; a projectile moves horizontally at const...
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Depression is a disease that afflicts the human psyche in such a way that the afflicted tends to act and react abnormally toward others and themselves. Therefore it comes to no surprise to discover that adolescent depression is strongly linked to teen suicide. Adolescent suicide is now responsible for more deaths in youths aged 15 to 19 than card...
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Homework #3b - II: Show your work under each question 1) You are riding your bike on a track that forms a vertical circular loop. If the diameter of the loop is 10.0 m, what is the minimum speed required for you to make it around the loop? 2) You are swinging a bucket of water in a vertical circle. Assuming that the radius of the rotation of...
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Visiting Researcher, The Foresight Institute P.O. Box 61058, Palo Alto, CA 94306 USA hanson@charon.arc.nasa.gov 510-651-7483 To appear in Social Epistemology, 1992. (version appeared: in Proc. Eighth Intl. Conf. on Risk and Gambling, London, 7/90.) C O U L D G A M B L I N G S A V E S C I E N C E? Encouraging an...