Two infinitely long wires each carrying the same current and pointing in $$+y$$ direction are placed in the $$x y$$-plane, at $$x=-2 \mathrm{~cm}$$ and $$x=1 \mathrm{~cm}$$. An electron is fired with speed $$u$$ from the origin making an angle of $$+45^{\circ}$$ from the $$X$$-axis. The force on the electron at the instant it is fired is
[$$B_0$$ is the magnitude of the field at origin due to the wire at $$x=1 \mathrm{~cm}$$ alone].
Two electrons, $$e_1$$ and $$e_2$$ of mass $$m$$ and charge $$q$$ are injected into the perpendicular direction of the magnetic field $$B$$ such that the kinetic energy of $$e_1$$ is double than that of $$e_2$$. The relation of their frequencies of rotation, $$f_1$$ and $$f_2$$ is
A compass needle oscillates 20 times per minute at a place where the dip is $$45^{\circ}$$ and the magnetic field is $$B_1$$. The same needle oscillates 30 times per minute at a place where the dip is $$30^{\circ}$$ and magnetic field is $$B_2$$. Then, $$B_1: B_2$$ is
A plane electromagnetic wave travels in free space along $$Z$$-axis. At a particular point in space, the electric field along $$X$$-axis is $$8.7 \mathrm{~Vm}^{-1}$$. The magnetic field along $$Y$$-axis is