Two parallel very long straight wires carrying current of $5 \text{ A}$ each are kept at a separation of $1 \text{ m}$. If the currents are in the same direction,the force per unit length between them is . . . . . . $\text{N/m}$. $(\mu_0 = 4\pi \times 10^{-7} \text{ SI units})$

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?

$A$ uniform magnetic field of $1.5\; T$ exists in a cylindrical region of radius $10.0\; cm$,its direction parallel to the axis along east to west. $A$ wire carrying current of $7.0\; A$ in the north to south direction passes through this region. What is the magnitude and direction of the force on the wire if,
$(a)$ the wire intersects the axis,
$(b)$ the wire is turned from $N-S$ to northeast-northwest direction,
$(c)$ the wire in the $N-S$ direction is lowered from the axis by a distance of $6.0 \;cm?$

Define $1 \ A$ (Ampere) using the force between two current-carrying parallel wires.

$A$ square loop of edge length $2 \ m$ carrying current of $2 \ A$ is placed with its edges parallel to the $x-y$ axis. $A$ magnetic field is passing through the $x-y$ plane and expressed as $\vec{B}=B_0(1+4x) \hat{k}$,where $B_0=5 \ T$. The net magnetic force experienced by the loop is . . . . . . $N$.