Two currents- carrying wires may attract each other. In
absence of other forces, the wires will move towards each
other increasing the kinetic energy . Does it contradict
the fact that the magnetic force cannot do any work and
hence cannot increase the kinetic energy?

Two bar magnets are placed close to each other with their opposite poles facing each other. In absence of other forces, the magnets are pulled towards each other and their kinetc energy increases. Does it contradict our earlier knowledge that magnetic forces cannot do any work and hence cannot increase kinetic energy of a system?

Can kinetic energy of a system be increased without applying any external force on the system?

Two objects which are initally at rest, move towards each other under the action of their internal attraction. If their speeds are 4 v and 2 v at any instant, then the speed of centre of mass of the system will be

Two wires carrying equal currents i each, are placed perpendicular to each other, just avoiding a contact. If one wire is held fixed and the other is free to move under magnetic forces, what kind of motion wil results?

Two particles P and Q move towards with each other from rest with the velocities of 1 and 20 ms^(-1) under the mutual force of attraction. The velocity of centre of mass is

Three coplanar parallel wires, each carrying a current of 10 A along the same direction, are placed with a separation 5.0 cm between the consecutive ones. Find the magnitude of the magnetic force per unit length acting on the wires.

Two proton beams going in the same direction repel each other whereas two wires carrying currents in the same direction attract each other. Explain.

Two long, straight wires, each carrying an electric current of 5.0 A, are kept parallel to each other at a separation of 2.5 cm. Find the magnitude of the magnetic force experienced by 10 cm of a wire.