The last geomagnetic reversal for Earth was about 780,000 years ago. The historic reversal rate for Earth seems to be once every few hundred thousand years, but it has varied widely; on at least two occasions, the field has maintained one polarity for tens of millions of years.

The reversal was dated to approximately 15 million years ago. In August 2018, researchers reported a reversal lasting only 200 years. But a 2019 paper estimated that the most recent reversal, 780,000 years ago, lasted 22,000 years.

about 22,000 years

IPE 14 1) At Earth’s pole, a compass needle will not show any particular direction in horizontal plane.

When it comes to magnets, opposites attract. This fact means that the north end of a magnet in a compass is attracted to the south magnetic pole, which lies close to the geographic north pole. Magnetic field lines outside of a permanent magnet always run from the north magnetic pole to the south magnetic pole.

Magnetic dip, dip angle, or magnetic inclination is the angle made with the horizontal by the Earth’s magnetic field lines. This angle varies at different points on the Earth’s surface.

Magnetic lines form continuous closed loops because magnetic monopole does not exist in nature. We always find magnetic poles – North and South pole which are coupled together in such a way that field lines originating from one pole ends at the another loop, forming a closed loop.

a) Why are the field lines repelled when a diamagnetic material is placed in an external. uniform magnetic field . This is because when any diamagnetic material is placed into a magnetic field its atoms acquire an induced magnetic moment pointing in a direction opposite to that of the external field.

A MAGNETISED NEEDLE IN A UNIFORM MAGNETIC FIELD EXPERIENCES A TORQUE BUT NO NET FORCE. HOWEVER, AN IRON NAIL NEAR A BAR MAGNET EXPERIENCES A FORCE OF ATTRACTION IN ADDITION TO TORQUE.

“Yes, the field lines repelled when a diamagnetic material is placed in an external uniform magnetic field. This is because of the fact that diamagnetic material has paired electron and they create a magnetic field which opposes the external magnetic field. A weak magnetism is induced in the same direction.

Magnetic field lines are closed curves as they propagate from the North pole outside the magnet’s body to the magnet’s body and from the south pole to the north pole inside the magnet’s body. Hence, the magnetic field lines are closed.

Properties of magnetic lines of force Magnetic lines do not intersect with one another. The magnetic lines strength is the same throughout, and it is proportional to how near the lines are.

Magnetic field lines are a visual tool used to represent magnetic fields. They describe the direction of the magnetic force on a north monopole at any given position. One useful analogy is the close connection between magnetic monopoles and electric charges.