$A$ power line lies along the east-west direction and carries a current of $10\, A$. The force per metre due to the earth's magnetic field of ${10^{ - 4}}\, T$ is

The magnetic force on a current-carrying wire in an external uniform magnetic field depends on:

$A$ current of $10 \text{ A}$ flows through a horizontal straight wire $A$ with both ends rigidly fixed. Wire $B$ is placed directly above and parallel to $A$. The weight per unit length of wire $B$ is $40 \times 10^{-3} \text{ N/m}$ and it carries a current of $20 \text{ A}$. Find the distance of wire $B$ from wire $A$ so that wire $B$ remains at rest. Also,state the direction of current flowing through it.

Two parallel conductors carrying unequal currents in the same direction . . . . . .

$A, B$ and $C$ are three parallel conductors of equal lengths and carry currents $I, I$ and $2I$ respectively as shown in the figure. The distance between $A$ and $B$ and between $B$ and $C$ is $d$. If $F_1$ is the force exerted by $B$ on $A$ and $F_2$ is the force exerted by $C$ on $A$,then:

$A$ 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......$^o$