A proton moving with a constant velocity passes through a region of space without any change in its velocity. If $\vec{E}$ and $\vec{B}$ represent the electric and magnetic fields respectively, then the region of space may have :

($A$) $\mathrm{E}=0, \mathrm{~B}=0$

($B$) $\mathrm{E}=0, \mathrm{~B} \neq 0$

($C$) $\mathrm{E} \neq 0, \mathrm{~B}=0$

($D$) $\mathrm{E} \neq 0, \mathrm{~B} \neq 0$

Choose the most appropriate answer from the options given below :

A square loop of area $25\,cm ^2$ has a resistance of $10\,\Omega$. The loop is placed in uniform magnetic field of magnitude $40.0 T$. The plane of loop is perpendicular to the magnetic field. The work done in pulling the loop out of the magnetic field slowly and uniformly in $1.0 sec$, will be $..........\times 10^{-3}$

The horizontal component of earth's magnetic field at a place is $3.5 \times 10^{-5} \mathrm{~T}$. A very long straight conductor carrying current of $\sqrt{2} A$ in the direction from South east to North West is placed. The force per unit length experienced by the conductor is$..............$ $\times 10^{-6} \mathrm{~N} / \mathrm{m}$.

A conducting loop carrying a current $I$ is placed in a uniform magnetic field pointing into the plane of the paper as shown. The loop will have a tendency to

A metallic loop is placed in a magnetic field. If a current is passed through it, then

Three long, straight parallel wires carrying current, are arranged as shown in figure. The force experienced by a $25\, cm$ length of wire $C$ is