Magnetostatics Objectives Part 06
101 . When a magnet is in motion relative to a coil the induced emf does not depend upon resistance of the coil
102 . Lenz’s law is a consequence of the law of conversation of energy
103 . An average voltage of 20V is induced in a 500-turn solenoid as the result of a change in flux which occurs in 0.5 second. The total flux change is 0.02 Wb
104 . A 1000 turn solenoid develops an average induced voltage of 120V. Over what time internal must a flux change 60 mWb occurs to produce such a voltage 0.5sec
105 . Diagram Question—
106 . Diagram Question—
107 . Diagram Question—
108 . A small piece of wire is dropped through the gap between poles of a magnet in 0.1 second. An emf of 6×10-3 V is induced in the wire. The magnetic flux between the poles is 4 x 10-4
109 . A multi-layer coil of turns of fine wire carrying 5A is 20mm long and has a thickness 5mm of winding. The mmf generated is 10 A-t
110 . On tripling the number of turns of a coil the inductance becomes 9 times as large
111 . tesla = 1Wb/m2
112 . A magnetic material has a total flux B of 80microWb with an mmf of 160At. The reluctance in ampere turns per weber is 2 x 10-6
113 . Super-magnetic materials are composed of an assemblage of ferromagnetic particles in a non-ferromagnetic matrix
114 . Diagram Question—
115 . A long solenoid of 2000 turns is 0.8m long. Magnetizing force in the center of this solenoid, if the exciting current is 2A is 5000AT/m
116 . The force required to separate two surfaces with a constant area measuring 5cm by 6cm when the flux density normal to the surface is 0.8tesla, will be 765N
117 . An electric current is flowing in an infinitely long straight conductor. The magnetic field at a distance of 4cm from the wire is 0.6 gauss. The magnetic field at a distance of 2cm from the wire will be 0.12 gauss
118 . A conductor of 0.2 meter long is carrying a current of 30 amperes at right angle to a magnetic field of 0.4 tesla. The force acting on the conductor will be 2.4N
119 . A conductor carries 250 amperes of current under 60o to a magnetic field of 1.1tesla. The force on the conductor will be nearly 240N
120 . A conductor of 1.5 min length carrying a current of 100 amperes at a right angle to a magnetic field having a flux density of 0.67 tesla. The force acting on the conductor will be 100N
