A straight wire of mass 250 g and length 2.5 m carries a current of 4 A . It can be suspended in mid air by a uniform horizontal magnetic field of magnitude:

A current carrying closed loop in the form of a right isosceles triangle XYZ is placed in a uniform magnetic field $B$ acting along $X Y$ of the loop. If the magnetic force on the arm $Y Z$ is $\sqrt{2} F$, then the force on the arm $X Z$ is:

Which physical quantity has the unit joule / tesla?

In to a uniform transverse magnetic field, two charged particles having the same mass and charge enter and move in two different circular paths. The ratio of the radii of curvatures of the circular paths is $1: 4$. What would be the ratio of their respective velocities?