### 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**