A very long thin strip of metal of width 'b' carries a current I along its length as shown in figure



Find the magnitude of magnetic field in the plane of the strip at a distance 'a' from the edge nearest to the point.

The graph showing the variation of the magnetic field strength (B) with distance (r) from a long current carrying conductor is

Four infinitely long parallel wires pass through the four corners of a square $PQRS$ of side $a$ that lies in a plane perpendicular to the wires (see figure).

They all carry equal steady currents $I$. Currents in the wires passing through $P$ and $Q$ point out of the page, and the currents in the wires passing through $R$ and $S$ point into the page as shown in the figure. The magnitude of the magnetic field at the centre $O$ of the square is 

Two long straight wires vertically pierced the plane of the paper at vertices of an equilateral triangle as shown in figure. They each carry $2 \mathrm{A},$ out of the paper. The magnetic field at the third vertex $P$ has magnitude.

Two long straight parallel conductors carry steady current ${\mathrm{l}}_1\mathrm{and} {\mathrm{l}}_2$ separated by a distance $\text{'}\mathrm{d}\text{'}$ if the currents are flowing in the same direction show how the magnetic field set up in one produces an attractive force on the other. Obtain the expression for this force. Hence define one ampere

A long straight wire of circular cross-section (radius $a$) is carrying steady current $\mathrm{I}.$ The current $\mathrm{I}$ is uniformly distributed across this cross-section. The magnetic field is

Obtain an expression for the magnetic induction at a point due to an infinitely long straight conductor carrying current.

An electric current I flows through an infinitely long conductor as shown in Figure below. Write an expression and direction for the magnetic field at point P.

Two very long, straight, and insulated wires are kept at $90°$ angle from each other in $\mathrm{x}\mathrm{y}$ plane as shown in the figure.

These wires carry currents of equal magnitude $I$ , whose direction are shown in the figure. The net magnetic field at point $P$ will be: