A current carrying coil is placed with its axis perpendicular to $ N-S $ direction. Let horizontal component of earth's magnetic field be $H_o$ and magnetic field inside the loop is $H$. If a magnet is suspended inside the loop, it makes angle $\theta $ with $H$. Then $\theta $$=$
${\tan ^{ - 1}}\left( {\frac{{{H_0}}}{H}} \right)$
${\tan ^{ - 1}}\left( {\frac{H}{{{H_0}}}} \right)$
$cosec^{ - 1}\left( {\frac{H}{{{H_0}}}} \right)$
${\cot ^{ - 1}}\left( {\frac{{{H_0}}}{H}} \right)$
A compass needle whose magnetic moment is $60 \,amp × m^2$ pointing geographical north at a certain place, where the horizontal component of earth's magnetic field is $40\, \mu Wb/m^2$, experiences a torque $1.2 \times {10^{ - 3}}\,N \times m.$ What is the declination at this place......$^o$
Name the elements of the earth’s magnetic field.
Tell the proper reason for the earth’s magnetic field to occur.
At an angle of $30^{\circ}$ to the magnetic meridian, the apparent dip is $45^{\circ} .$ Find the true dip :
At the magnetic north pole of the earth, the value of horizontal component of earth's magnetic field and angle of dip are, respectively