Explain geographic meridian and magnetic meridian.
$(i)$ Geographic meridian : Consider a point on the Earth's surface. At such a point, the direction of the longitude circle determines the geographic north-south direction, the line of longitude towards the north pole being the direction of true north.
Definition : The vertical plane containing the longitude circle and the axis of rotation of Earth is called the geographic meridian.
$(ii)$ Magnetic meridian (Definition): The vertical plane at a place on the Earth passes through the imaginary line joining the magnetic north and the south pole is called magnetic meridian.
Define geographic meridian. and Define magnetic meridian.
The magnetic needle of a tangent galvanometer is deflected at an angle $30^o$ due to a magnet. The horizontal component of the earth's magnetic field is $0.34 \times 10^{-4}\,T$ which is along the plane of the coil. The magnetic field due to magnet is
The earth's magnetic field was flipped by $180^{\circ}$ a million years ago. This flip was relatively rapid and took $10^5 \,yrs$. Then, the average change in orientation per year during the flip was closest to ............ $s$
If magnetic lines of force are drawn by keeping magnet vertical, then number of neutral points will be
A bar magnet is situated on a table along east-west direction in the magnetic field of earth. The number of neutral points, where the magnetic field is zero, are