Two long straight wires $P$ and $Q$ carrying equal current $10\,A$ each were kept parallel to each other at $5\,cm$ distance. Magnitude of magnetic force experienced by $10\,cm$ length of wire $P$ is $F_1$. If distance between wires is halved and currents on them are doubled,force $F_2$ on $10\,cm$ length of wire $P$ will be :

$A$ current of $5 \ A$ is flowing in a wire of length $1.5 \ m$. $A$ force of $7.5 \ N$ acts on it when it is placed in a uniform magnetic field of $2 \ T$. The angle between the magnetic field and the direction of the current is......$^o$

Three long,straight and parallel wires carrying currents are arranged as shown in the figure. The wire $C$ which carries a current of $5.0\, A$ is so placed that it experiences no force. The distance of wire $C$ from wire $D$ is (in $, cm$)

$A$ horizontal semi-circular wire of radius $r$ is connected to a battery through two similar springs $X$ and $Y$. The battery sends a current $I$ through the wire. $A$ uniform magnetic field $B$ is applied perpendicular to the plane of the wire, as shown in the figure. What is the force acting on each spring?

$A$ 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 $30^{\circ}$ with the horizontal. The rod is prevented from sliding down by passing a current through it,while a magnetic field of induction $0.25\; T$ acts on it in the vertical direction. The current flowing in the rod to keep it stationary is: (in $; A$)

$A$ conductor of length $l$ and mass $m$ is placed along the east-west line on a table. Suddenly,a certain amount of charge is passed through it and it is found to jump to a height $h$. The earth's magnetic induction is $B$. The charge passed through the conductor is: