The work done by a normal magnetic field in revolving a charge particle q in a circular path will be zero.

Figure below shows three circuits consisting of concentric circular arcs and straight radial lines. The center of the circle is shown by the dot. Same current flows through each of the circuits. If $B_1, B_2, B_3$ are the magnitudes of the magnetic field at the center. Which of the following is true?

A wire $A$, bent in the shape of an arc of a circle, carrying a current of $2 \mathrm{A}$ and having radius $2 \mathrm{cm}$ and another wire $B$, also bent in the shape of an arc of a circle, carrying a current of $3 \mathrm{A}$ and having radius of $4\text{ cm}$, are placed as shown in the figure. The ratio of the magnetic fields due to the wires $\text{A}$ and $\text{B}$ at the common centre $\text{O}$ is:

What is the magnetic field at the centre of arc in the figure below? 

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.

Find the magnetic field at point $\mathrm{P}$ due to a straight line segment $\mathrm{A}\mathrm{B}$ of length $6 \mathrm{c}\mathrm{m}$ carrying a current of $5 \mathrm{A}.$ (See figure) $\left({\mu }_0=4\pi \times {10}^{-7} {\mathrm{NA}}^{-2}\right)$

Write Biot-Savart's law in vector form.

A wire carrying current $\text{I}$ has the shape as shown in adjoining figure. Linear parts of the wire are very long and parallel to $\text{X}$ -axis while semicircular portion of radius $\text{R}$ is lying in $\text{Y}$ -$\text{Z}$ plane. Magnetic field at point $\text{O}$ is :

An electric current I flows through a circular loop as shown in Figure below. Write an expression and direction for the magnetic field at the centre of the loop at point $\mathrm{P}$.

A long straight wire carrying electric current $\text{'}i \text{'}$is bent at its mid point to form an angle of $45°$ as shown in the figure. Magnetic field at a point $P$ at a distance $d$ from the point $Q$ of bending is

As shown in the figure, two infinitely long, identical wires are bent by ${90}^o$ and placed in such a way that the segments $LP$ and $QM$ are along the $x$ - axis, while segments $PS$ and $QN$ are parallel to the $y$ - axis. If $OP=OQ=4cm,$ and the magnitude of the magnetic field at $O$ is ${10}^{-4} T,$ and the two wires carry equal currents (see figure), the magnitude of the current in each wire and the direction of the magnetic field at $O$ will be $\left({\mu }_0=4\pi \times {10}^{-7}N{A}^{-2}\right):$