A tightly wound solenoid of radius 'a' and length 'l' has 'n' turns per unit length.It carries an electric current 'i'.Consider a length 'dx' of the solenoid at a distance 'x' from one end.This contains 'ndx' turns and may be approximated as a circular current 'indx'(a)Write the magnetic field at the centre of the solenoid due to thiscircular current.Integrate this expression under proper limits to find the magnetic field at the centre of the solenoid.(b)Verify that if l>>a,the field tends toB=u0ni and if a>>l,the field tends to B=u0ni/2a.ANS:-(a)u0ni/[1+(2a/l)2]1/2HURRY UP............

Radhika Batra , 10 Years ago

Grade 11