As shown in the figure,a wire is bent to form a $D$-shaped loop carrying current $I$,where the curved part is a semi-circle of radius $R$. The loop is placed in a uniform magnetic field $\overrightarrow{B}$,which is directed into the plane of the paper. The net magnetic force on the closed loop is:

$A$ straight wire is placed in a magnetic field that varies with distance $x$ from the origin as $\vec{B} = B_0 \left( 2 - \frac{x}{a} \right) \hat{k}$. The ends of the wire are at $(a, 0)$ and $(2a, 0)$ and it carries a current $I$ in the positive $x$-direction. If the force on the wire is $\vec{F} = IB_0 \left( \frac{ka}{2} \right) \hat{j}$,then the value of $k$ is:

Two long and parallel straight wires $A$ and $B$ carrying currents of $10 \ A$ and $4 \ A$ in the same direction are separated by a distance of $2 \ cm$. Estimate the force on a $4 \ cm$ section of wire $A$. ( $\mu_0 = 4 \pi \times 10^{-7} \ SI$ ).

Two thin long parallel wires,separated by a distance $d$,carry a current of $I$ $A$ in the same direction. They will:

Two thin,long,parallel wires,separated by a distance $d$,carry a current of $i$ in the same direction. They will

Two parallel conductors,each $50 \ m$ long,separated by $0.2 \ m$,experience a force of $1 \ N$. If the current in the first conductor is twice that of the second conductor,what is the current in the second conductor (in $A$)? (Given: $\mu_0 = 4 \pi \times 10^{-7} \ T \cdot m/A$)