Question

The point where the resultant magnetic field intensity due to the earths field and magnet is zero called....

Answer 1

The points where the resultant magnetic field intensity due to the earth field and magnet is zero called $\bf{neutral\: point}$.
Let B is magnetic field due to magnet
H is magnetic field intensity of earth magnet.
so, $(B -H) &= 0 \\ \text {or,} \: B &= H \\ \text {or,} \: \frac {\mu _0}{4\pi } \frac {2Md}{(d^2 - l^2)^2} &= H\\ \text {or,} \: M &= \frac {4\pi }{\mu _0 } \frac {(d^2 -l^2)^2}{2d} H \\ \text {If the magnet has very short length, then} \\ M &= \frac {2\pi }{\mu _0} d^3 H$
Here M is magnetic moment of magnet.

Answer 2

The answer is neutral point.

The point where the resultant magnetic field intensity due to the earth’s field and magnet is zero is called neutral point. Neutral point is also known as null point. When you keep a compass needle is placed in this point, it will remain in any direction. However, when it is placed beyond the neutral point, the needle alignment will be such that its north pole is always towards the northern direction.