The magnitude of the net magnetic field at point $P$ is $5.77\times {10}^{-n} \mathrm{T}$as shown in the figure? If two loops of wire carry the same current of $10 \mathrm{mA}$, but the flow of current is in opposite directions. One loop has a radius of $R_1=50 \mathrm{cm}$ and the other loop has a radius of $R_2=100 \mathrm{cm}$. From the first loop to the point $\left(P\right)$, the distance is $0.25 \mathrm{m}$, and from the second loop to the point, the distance is $0.75 \mathrm{m}$ from the point$\left(P\right)$. Find the value of $n$.

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

The magnetic field at the centre ${}^{\text{'}}O^{\text{'}}$ in the given figure is

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:

The magnetic field at the centre $O$ of the current-carrying square loop shown in the figure is