NEET Questions

A solid sphere of uniform density $\rho$ and radius $R$ has a concentric spherical cavity of radius $R/2$. The gravitational field at a distance $r = R/4$ from the center is:

A uniformly charged non-conducting sphere of radius $R$ and charge $Q$ has electric potential $V_0$ at its center. If a spherical cavity of radius $R/2$ is carved out symmetrically, such that the center of the cavity is at a distance $R/2$ from the center of the sphere, what is the electric potential at the center of the cavity?

Two point charges +q and -2q are placed a distance 'd' apart. At what distance along the line joining the two charges is the electric potential zero?

Two concentric conducting spherical shells of radii $R_1$ and $R_2$ ($R_2 > R_1$) carry charges $Q_1$ and $Q_2$ respectively. The potential difference between the shells is:

Two identical short bar magnets, each of magnetic moment $M$, are placed perpendicular to each other at a distance $d$ apart. The magnetic field at a point midway between them on the line joining their centers is:

Two short bar magnets of magnetic moments 'M' each are arranged at the opposite corners of a square of side 'd' such that their centres coincide with the corners and their axes are parallel. If the like poles are in the same direction, the magnetic induction at any of the other corners of the square is:

Two infinitely long parallel wires carry currents $I_1$ and $I_2$ in the same direction. The distance between the wires is $d$. A point P lies in the plane of the wires at a distance $x$ from the wire carrying current $I_1$. If the magnetic field at P is zero, the ratio $I_1/I_2$ is:

A square loop of side $a$ carries a current $I$. A long straight wire carrying current $I$ is placed in the plane of the loop parallel to one of its sides at a distance $a$ from that side. The net force on the loop due to the wire is:

Two coaxial circular coils of radii $a$ and $b$ ($a < b$) carry currents $I_1$ and $I_2$ respectively. If the resultant magnetic field at the center is zero, the ratio of $I_1/I_2$ is:

Two infinitely long, parallel wires carry currents $I_1$ and $I_2$ in the same direction. The distance between the wires is 'd'. A point P lies in the plane of the wires at a distance 'x' from wire 1. If the magnetic field at P is zero, and $I_1 = 2I_2$, which of the following relations is correct?