# Second Year Physics Electromagnetism

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$14.8. Derlve the general equation for Induced emf begining with the law of force in a current carrying conducto: in a magnetic fleld.$

$The SI unit of magnetic induction is tesla which is also equal to:A) Newton / ampere-meter or N/A-mB) Newton / ampere-meter { }^{2} or N/A-m { }^{2} C) Newton / ampere { }^{2} -meter or N / A^{2}-m D) None of these$

$14.11. An cm of 45 \mathrm{~m} .volt is Induced In a coll of 500 turns. when the current in a nelghbouring coil changes from 10 amps to 4 amps in 0.2 seconds.b) What is the rate of change of fux in the second coll?$

$14.12. An Iron core solenold with 400 turns has a cross section area of 4.0 \mathrm{~cm}^{2} . A current of 2 amp passing through it produces \mathrm{B}=0.5 webers-m { }^{-2} . How targe an emf is induced in it. If the current is twrned of in 0.1 seconds. What is the self Inductance of the solenold ? (Ans 0.8 \mathrm{~V} L=40 \mathrm{mh} ).$

$15.12. What is a transformer? Explain the working of a transformer in connection with mutual induction.$

$15.2. A step-up transformer has a turn ratios of 1: 100 . An alternating supply of 20 \mathrm{~V} is connected across the primary coil. What is the secondary voltage? Ans. (2000 V)$