
Two long straight parallel wires are apart, perpendicular to the plane of the paper, Fig. The wire A carries a current of , directed into the plane of the paper. The wire carries a current such that the magnetic field of induction at the point , at distance from the wire is zero. Find The force per unit length on the wire .



Important Questions on Electromagnetism
A wire loop carrying a current is placed in the plane as shown in Fig. If a particle with charge and mass is placed at the centre and given a velocity along . Find its instantaneous acceleration.

A wire loop carrying a current is placed in the - plane as shown in Fig. acceleration. If an external uniform magnetic induction field is applied, find the force and the torque acting on the loop due to this field.

An electron gun G emits electrons of energy travelling in the positive -direction. The electrons are required to hit the spot where , and the line make an angle with the -axis is as shown in Fig. A uniform magnetic field parallel to exists in the region outside the electron gun. Find the minimum value of needed to make the electron hit .

A long horizontal wire , which is free to move in a vertical plane and carries a steady current of , is in equilibrium at highest of over another parallel long wire which is fixed in a horizontal plane and carries a steady current of , as shown in figure. Show that when is slightly depressed, it executes simple harmonic motion. Find the period of oscillations.



The region between and is filled with a uniform steady magnetic field . A particle of mass , positive charge and velocity travels along -axis and enters the region of the magnetic field. Neglect the gravity throughout the question.
(a) Find the value of if the particle emerges from the region of the magnetic field with its final velocity at an angle to its initial velocity.

The region between and is filled with a uniform steady magnetic field . A particle of mass , positive
charge and velocity travels along -axis and enters the region of the magnetic field. Neglect the gravity throughout the question.
(b) Find the final velocity of the particle and the time spent by it in the magnetic field, if the magnetic field now expands upto .
