|
A solenoid is a long coil (shaped like a cylinder) containing a large number of close turns of insulated copper wire.
The figure above shows a solenoid SN whose ends are connected to a battery B through a switch X. When a current is passed through a solenoid, it produces a magnetic field around it. The magnetic field is shown in the fig. It is along the axis of the solenoid and is almost constant in magnitude and direction. The magnetic lines of force inside the solenoid are nearly parallel to each other and parallel to the axis of the solenoid.
A solenoid when suspended freely, aligns itself in the north-south direction, thus behaving like a bar magnet. One end of the solenoid acts like a north pole and the other end the south pole.
The polarity of the solenoid can be changed by reversing the direction of the current.
The strength of the magnetic field produced by a current carrying solenoid depends on:
- The number of turns - larger the number of turns, greater is the magnetism produced
- The strength of the current - when current increases, magnetism also increases
- Nature of 'core-material' used in making the solenoid - if we use soft-iron as a core for the solenoid, then it produces the strongest magnetism
| 
