What is the fundamental difference between an electric dipole and a magnetic dipole? 

A conductor has 3 segments: two starlight and of length L each and a semicircular with radius R. It carries a current I. What is the magnetic field B at point P?

Figure a, b show two Amperian loops associated with the conductors carrying current I in the sense shown. The $\text{∮}\overrightarrow{\mathrm{B}}\cdot \mathrm{d}\overrightarrow{\mathrm{l}}$in the cases a and b will be, will be respectively, 

A proton enters a perpendicular uniform magnetic field B at origin along the positive x-axis with a velocity v as shown in the figure. Then it will follow the following path. [The magnetic field is directed into the paper].

A piece of straight wire has mass $20 \mathrm{g}$ and length $1 \mathrm{m}$. It is to be levitated using a current of 1 A flowing through it and a perpendicular magnetic field B in a horizontal direction. What must be the magnetic of B? 

Calculate the value of magnetic field at a distance of $2 \mathrm{cm}$ from a very long straight wire carrying a current of 5 A

(Given: ${\mathrm{\mu }}_0=4\mathrm{\pi }\times {10}^{-7}\mathrm{Wb}/\mathrm{Am}$)