SAMPLE QUESTIONS
1. Two identical conducting wires AOB and COD are placed at right angle to each other. The wire AOB carries an electric current I
1 and COD carries a current I
2. The magnetic field on a point lying at a distance d from O, in a direction perpendicular to the plane of the wires AOB and COD, will be given by
a) $\frac{\mu_{0}}{2\pi}\left (\frac{I_{1} + T_{2}}{d} \right )^{1/2}$
b) $\frac{\mu_{0}}{2\pi d}\left (I_{1}^{2} + I_{2}^{2} \right )^{1/2}$
c) $\frac{\mu_{0}}{2\pi d}\left (I_{1} + I_{2} \right )$
d) $\frac{\mu_{0}}{2\pi d}\left (I_{1}^{2} + I_{2}^{2} \right )$
2. A thin circular disk of radius R is uniformly charged with density σ > 0 per unit area. The disk rotates about its axis with a uniform anguilar speed ω. The magnetic moment of the disk is
a) 2πR
4ω
b) πR
4σω
c) $\frac{\pi R^{4}}{2}\sigma \omega$
d) $\frac{\pi R^{4}}{4}\sigma \omega$