physics for jkssb teacher short notes by home academy

short notes on magnetism by er afzal ahamed malik

1.The magnetic effect of electric current was discovered by

 oersted in 1820.It was mathematically explained by biot and savart.

2.The product of current I and elementary length dl of the

 current carrying conductor is given by Idl .the direction of

 current carrying element is same as that of electric current.

3.MAGNETIC FIELD the region of space around a magnet ,

 current carrying conductor or a moving charge , in which

 magnetic effect can be experienced is called magnetic field.

4.Magnetic induction the magnetic field strength is called

 magnetic induction. It is denoted by B vector.magnetic induction

 is a vector quantity.

5.The lines of magnetic induction are closed curves.

6.The unit of magnetic field is tesla (weber/m²). Cgs unit is

 gauss or mx/cm²

7.1tesla=10⁴gs

8.The lines of magnetic induction for uniform magnetic

 field are parallel and equally spaced. But for the non

 uniform magnetic field are curves or unequally spaced or both.

9. the current element plays the same role in producing 

a magnetic field as the point charge does in producing

 the electric field.

10. biot savart law is analogue  of the columb law in electrostatics.

11.cyclotron constist of two dees , placed in a strong magnetic

 field .oscillating electric field is applied to the two dees from 

an oscillator . the magnetic field is perpendicular to the electric field .

 the electric field exixt only across the gap between the dees.

Note:Cyclotron can not be used to accelerate the electrons

 because electrons move with the velocities of light.

12. parallel current carrying conductors attract each other.

13. antiparallel current carrying conductors repell each other.