16%20-%20Magnetic%20Effects%20of%20Currents

# 16%20-%20Magnetic%20Effects%20of%20Currents - 16 MAGNETIC...

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16 - MAGNETIC EFFECTS OF CURRENTS Page 1 ( Answers at the end of all questions ) 1 ) One conducting U tube can slide inside another as shown in the figure, maintaining electrical contacts between the tubes. The magnetic field B is perpendicular to the plane of the figure. If each tube moves towards the other at a constant speed V, then the emf induced in the circuit in terms of B, l and V where l is the width of each tube, will be ( a ) - BlV ( b ) BlV ( c ) 2BlV ( d ) zero [ AIEEE 2005 ] 2 ) Two thin, long, parallel wires, separated by a distance ‘d’ carry a current ‘i’ A in the same direction. They will ( a ) repel each other with a force of d π 2 i μ 2 o ( b ) attract each other with a force of d π 2 i μ 2 o ( c ) repel each other with a force of 2 2 d π 2 i μ o ( d ) attract each other with a force of 2 2 d π 2 i μ o [ AIEEE 2005 ] 3 ) A charged particle of mass m and charge q travels on a circular path of radius r that is perpendicular to a magnetic field B. The time taken by the particle to complete one revolution is ( a ) m B q π 2 2 ( b ) B mq π 2 ( c ) qB m π 2 ( d ) m qB π 2 [ AIEEE 2005 ] 4 ) A uniform electric field and a uniform magnetic field are acting along the same direction in a certain region. If an electron is projected along the direction of the fields with a certain velocity, then ( a ) its velocity will increase ( b ) its velocity will decrease ( c ) it will turn towards left of direction of motion ( d ) it will turn towards right of direction of motion. [ AIEEE 2005 ] 5 ) Two concentric coils each of radius equal to 2 π cm are placed at right angles to each other. 3 ampere and 4 ampere are the currents flowing in each coil respectively. The magnetic induction in weber / m 2 at the centre of the coils will be ( µ 0 = 4 π × 10 - 7 Wb / Am ) ( a ) 10 - 5 ( b ) 12 × 10 - 5 ( c ) 7 × 10 - 5 ( d ) 5 × 10 - 5 [ AIEEE 2005 ] 6 ) A current I ampere flows along an infinitely long straight thin walled tube, then the magnetic induction at any point inside the tube is ( a ) infinite ( b ) zero ( c ) r 2i . π 4 μ 0 tesla ( d ) r 2i tesla [ AIEEE 2004 ] 7 ) A long wire carries a steady current. It is bent into a circle of one turn and the magnetic field at the centre of the coil is B. It is then bent into a circular loop of n turns. The magnetic field at the centre of the coil will be ( a ) nB ( b ) n 2 B ( c ) 2nB ( d ) 2n 2 B [ AIEEE 2004 ]

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16 - MAGNETIC EFFECTS OF CURRENTS Page 2 ( Answers at the end of all questions ) 8 ) The magnetic field due to a current carrying circular loop of radius 3 cm at a point on the axis at a distance of 4 cm from the centre is 54 µ T. What will be its value at the centre of the loop ? ( a )
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16%20-%20Magnetic%20Effects%20of%20Currents - 16 MAGNETIC...

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