Force on current-carrying conductor, force between parallel currents
- A wire carrying a current I along the positive x-axis has length L. It is kept in a magnetic field B=(2i+3j-4k) T. The magnitude of the magnetic force acting on the wire is : Answer: 4. 5 IL Force on a wire: vec F=I vec L×vec B with vec L=Lhat i . hat i×(2hat i+3hat j-4hat k)=3hat k+4hat j (since hat i×hat j=hat k... 1
- A metallic rod of mass per unit length 0.5 kg m^-1 is lying horizontally on a smooth inclined plane which makes an angle of 30^° with the horizontal. The rod is not allowed to slide down by flowing a current through it when a magnetic field of induct… Answer: 4. 11.32 A For the rod to stay at rest on a smooth incline, the horizontal magnetic force must balance the component of weight down... 1
- An arrangement of three parallel straight wires placed perpendicular to plane of paper carrying same current 'I' along the same direction is shown in Fig. Magnitude of force per unit length on the middle wire 'B' is given by : Answer: 3. μ₀ i²/√(2)π d Key idea: parallel wires carrying current in the same direction attract each other, each pair giving a force per un... 1
- A square loop ABCD carrying a current i, is placed near and coplanar with a long straight conductor XY carrying a current I, the net force on the loop will be : Answer: 1. 2μ₀ Ii/3π Key idea: forces on the two sides parallel to the wire add up; forces on the other two sides cancel. Side nearest the w... 1