What was the recognition of Earth’s magnetic field ? State dynamo effect
Recognition of Earth's magnetic field was that a giant bar magnet placed along the axis of rotation of the Earth and deep in the interior. Magnetic field arising due to this reason. The magnetic field is now thought to arise due to electrical currents produced by convective motion of metallic fluids (consisting mostly of molten iron and nickel) in the outer core of the Earth, due to this reason magnetic arises. This is known as the dynamo effect.
Ratio between total intensity of magnetic field at equator to poles is
Two short bar magnets of magnetic moments $m$ each are arranged at the opposite corners of a square of side $d$ such that their centres coincide with the corners and their axes are parallel. If the like poles are in the same direction, the magnetic induction at any of the other corners of the square is
The angle of dip at a place on the earth gives
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 ............ $s$
A compass needle of oscillation magnetometer oscillates $20$ times per minute at a place $P$ of dip $30^{\circ}$. The number of oscillations per minute become $10$ at another place $Q$ of $60^{\circ} dip$. The ratio of the total magnetic field at the two places $\left(B_{Q}: B_{p}\right)$ is.