Essay on Faradays Law

1660 Words Jun 27th, 2015 7 Pages
LivePhoto Physics Activity 32 Name: Date:
Exploring Faraday’s Law
In 1820 Hans Christian Oersted observed that electric currents create magnetic fields. Consequently many scientists made unsuccessful attempts to create current in the presence of magnetic fields. After over 10 years of investigation Michael Faraday and Joseph Henry, working independently on different sides of the Atlantic, made the discovery that if a conducting coil has a changing magnetic flux passing through it an electromotive force is created that causes a current to flow through the coil. The equation describing this phenomenon quantitatively is known as Faraday’s Law. a b c In this activity you will be asked to use Faraday’s Law to explain why the
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Variation of Flux Passing though a Coil in the Vicinity of a Rod Shaped Magnet: The direction of the magnetic flux lines associated with a cylindrical magnet are shown in Figure 2 and the area vector associated with the coil is shown in Figure 3. By convention if the coil’s area vector and the flux line direction are in the same direction, the flux passing through the coil is positive. If the flux line direction and the A vector direction are opposite, then the flux passing through the coil is negative. i Figure 3: The coil in the movie is wired so its area vector points to the right.
N
S Figure 2: External flux lines point away from a north pole and toward a south pole.
1. Preliminary Questions (a) : Negative Positive Zero
Recall that change is the difference between the final value of a quantity and its initial value. If the north pole of the magnet is moved toward the left through the coil as shown in Figure 2, what is the sign of change of the flux lying in the plane of the coil? Answer= Negative (b) : Increases Decreases Stays the same
What happens to the absolute value of the rate of change of the flux in the area subtended by the coil, if the magnet is moved more rapidly through the coil? Answer= Increases (c) According to Faraday’s Law what happens to the absolute value of the maximum value of the induced emf if the magnet is moved more

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