If the magnetic force on a moving charged particle in a magnetic field becoms ______ the direction of motion of the particle, or its opposite direction, indicates the direction of magnetic field. [Fill in the blank

Explanation

Solar wind basically brings a stream of charged particles towards the Earth. When these particles enter the magnetic field of Earth then these particles are deviated away so that these may not reach Earth. But in this action some charged particles are thrown towards the polar regions. These particles are trapped around the magnetic poles of Earth. When these particles are nocelerated towards the atmosphere of Earth then these particles collide with oxygen and nitrogen present in the atmosphere to result in the emission of red and green light. So, this natural spectacular phenomenon takes place near magnetic poles to amuse us.