Magnetic field Magnetic field lines Magnitude & direction of magnetic force acting on a north pole Magnetic field line starts at north pole No intersection of magnetic field lines Magnetic field line ends at south pole N P.50
Solenoid with current Electromagnet can be strengthened Larger current Increase number of turns of coil Use soft iron core Electromagnet Direction of field lines can be reversed or alternate On or off any time P.56
P.59 Induced South pole is induced. S N M : North pole S Iron bar is attracted downwards 2 dots within 1 cycle 100 dots in 1 second
P.59 The soft iron bar is magnetized to attract the arm and hit the bell The arm will be attracted permanently.
P.60 Increase no. of turns per unit length To avoid the sparks when contacts touch each other Current flows through the circuit, magnetic field is produced and induced poles are produced on the contacts. They attract each other and conduct electricity. The soft iron is magnetized to attract the steel ball for a while Increase e.m.f. of cell
P.60 7a) Attract downwards Increase no. of turns per unit length Weaker spring to have greater extensions under same amount of force 7c) Same current -> Greater attractive force 7b) No.