The strength of the magnetic field around a straight wire :
2.
A magnetic needle is kept in non-uniform magnetic field.It experiences:
3.
A long wire carries a current of 20 A along the axis of a solenoid, the field due to the solenoid is 4 mT. The resultant field at a point 3 mm from the solenoid axis is :
Bwire=m0
4.
A circular current-carrying coil has a radius R. The distance from the center of the coil on the axis where the magnetic induction will be -^th of its value at the centre8of the coil, is :
Magnetic field on the axis of a circular coil having n turns is B = m0/4p 2pniR2/(R2+x2)3/2 1/8 m0/4p 2pni/R = m0/4p 2pniR2/(R2+x2)3/2
5.
Through two parallel wires P and Q, 10 A and 2 A ofcurrents are passed respectively in opposite directions.' Ifthe wire P is infinitely long and the length of the wireQ is 2 cm, the force on the conductor Q which is situatedat 10 cm distance from P, will be: