The magnetic field due to the earth is closely equivalent to that due to
A large magnet of length equal to the diameter of the earth
A magnetic dipole placed at the centre of the earth
A large coil carrying current
Neither of the above
At a certain place the angle of dip is $30^{\circ}$ and the horizontal component of earth's magnetic field is $0.5 G$. The earth's total magnetic field (in $G$ ), at that certain place, is ................
A dip needle vibrates in the vertical plane perpendicular to the magnetic meridian. The time period of vibration is found to be $2$ seconds. The same needle is then allowed to vibrate in the horizontal plane and the time period is again found to be $2$ seconds. Then the angle of dip is.....$^o$
Give information about Earth’s magnetism.
Consider the plane $\mathrm{S}$ formed by the dipole axis and the axis of earth. Let $\mathrm{P}$ be point on the magnetic equator and in $\mathrm{S}$. Let $\mathrm{Q}$ be the point of intersection of the geographical and magnetic equators. Obtain the declination and dip angles at $\mathrm{P}$ and $\mathrm{Q}$
A telephone cable at a place has four long straight horizontal wires carrying a current of $1.0\; A$ in the same direction east to west. The earth's magnetic field at the place is $0.39 \;G ,$ and the angle of dip is $35^{\circ} .$ The magnetic declination is nearly zero. What are the resultant magnetic fields at points $4.0\; cm$ below and above the cable?