Gravitational Field Intensity

Gravitational field intensity is the force per unit mass produced by a source mass, given by $E=\frac{GM}{r^2}$ and directed toward the source. It is a vector quantity, so contributions from several masses must be added as vectors, not as plain numbers. At the midpoint between two identical masses, each mass is at the same distance and produces a field of equal magnitude, but the two fields point in exactly opposite directions toward their respective masses. Their vector sum is therefore $E_{net}=E-E=0$. The option claiming twice the single-mass field wrongly adds the magnitudes as if both pointed the same way. The option equal to one mass ignores the second source entirely. The option infinite would only apply at the location of a point mass itself, not at the midpoint. This illustrates the NCERT principle of superposition for gravitational fields, which states that the total field at any point is the vector sum of the individual fields from each source mass acting independently. It is worth noting that although the net field, and hence the net force on a test particle, is zero at the midpoint, the gravitational potential there is not zero; potential is a scalar and the two negative contributions add rather than cancel. This distinction between a vanishing vector field and a non-zero scalar potential is a frequently tested subtlety. A sanity check confirms that by symmetry no preferred direction exists, so the net field must vanish.