At the magnetic north pole of the earth, the value of horizontal...

At the magnetic north pole, the magnetic needle will point vertically. There is no component of earth's magnetic field in the horizontal direction and the angle of dip (the angle that the resultant magnetic field at the place makes with the horizontal) is $90^{{}^{\circ}}$. $\mathrm{H}=0,$\delta=$90^{{}^{\circ}}(\text{ maximum })$