a solenoid is a long coil made of an elctricity conducting material which produces a magnetic field around it when current is passed through it..
when the magnetic field lines have to b drawn around a solenoid, then it has to b considered as a bar magnet. this is because each loop of the coil of the solenoid will have magnetic field loops around them which can b summed up and taken as big loops like dat of a bar magnet...
it should also b noted dat the magnetic field insid ethe current carrying solenoid will always b zero depsite whatever amount of current through the coil or any amount of magnetic field produced......
apart from the ncert books there are other reference books which deal this topic in a better manner like....
you can get better and detailed information on solenoid on:-
HI
a solenoid is a long coil made of an elctricity conducting material which produces a magnetic field around it when current is passed through it..
when the magnetic field lines have to b drawn around a solenoid, then it has to b considered as a bar magnet. this is because each loop of the coil of the solenoid will have magnetic field loops around them which can b summed up and taken as big loops like dat of a bar magnet...
it should also b noted dat the magnetic field insid ethe current carrying solenoid will always b zero depsite whatever amount of current through the coil or any amount of magnetic field produced......
apart from the ncert books there are other reference books which deal this topic in a better manner like....
you can get better and detailed information on solenoid on:-
http://www.wisegeek.com/what-is-a-solenoid.htm
en.wikipedia.org/wiki/Solenoid
Madhuri