Ls 4 - Magnetic Effects of Electric Current

Questions

1. in lenz law some dipoles are induced in such a way that they oppose the magnetic field that is being formed in the dielectric

2. Nishty Agarwal - Two long straight wires are placed along x-axis and y-axis. They carry a current I1 and I2 respectively. The equation of locus of zero magnetic induction in the magnetic field produced by them is a) y=x b) y=(I2/I1)x c) y=(I1/I2)x d)y=(I1 I2)x

3. Surface charge density on a ring of radius a and width d is sigma as shown in the figure. It rotates with frequency f about its own axis. Assume that the charge is only on outer surface. The magnetic field induction at centre is (d<<a) ?

4. Nishty Agarwal - A charged particle moves in a gravity free space without change in velocity. Which of the folowing is not possible a) E=0,B=0 b)E is not =0 , B=0 -> The answer c) E=0, B is not zero d) E is not zero, B is not zero -> Velocity selector concept