ch30-p035

# ch30-p035 - 35. (a) Letting x be the distance from the...

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consider an infinitesimal horizontal strip of length x and width dr , parallel to the wire and a distance r from it; it has area A = x dr and the flux is 0 2 B i dB d A x d r r µ π Φ= = . By Eq. 30-1, the total flux through the area enclosed by the rod and rails is 00 ln . 22 aL B a ix ix dr a L ra µµ ππ + + ⎛⎞ = ⎜⎟ ⎝⎠ According to Faraday’s law the emf induced in the loop is () ( ) 7 4 ln ln 4 10 T m/A 100A 5.00m/s 1.00cm 10.0cm ln 2.40 10 V. 2 1.00cm B ii v d d x dt dt a a ε Φ ++ == = π× + × (b) By Ohm’s law, the induced current is ( ) 44 / 2.40 10 V / 0.400 6.00 10 A. iR −− × = × A Since the flux is increasing the magnetic field produced by the induced current must be into the page in the region enclosed by the rod and rails. This means the current is clockwise. (c) Thermal energy is being generated at the rate 2 24 6.00 10 A 0.400 PiR × = A 7 1.44 10 W. × (d) Since the rod moves with constant velocity, the net force on it is zero. The force of the

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## This note was uploaded on 06/03/2011 for the course PHY 2049 taught by Professor Any during the Spring '08 term at University of Florida.

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ch30-p035 - 35. (a) Letting x be the distance from the...

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