Question

What is necessary to have a magnetic field?

Answer 1

Hi______________

for magnetic field we have continuous flow of charge particle .

it may be +ve or -ve ,doesn't matter,

we know that electric field are produced by any stationary charge particle .

but for magnetic field it must be in motion.

Magnetic field is always perpendicular to the Electric field.
hence current is flow i.e. charge is flow then magnetic field is produced.

u can ask me why earth have it magnetic field ,it have no charge flow inside the earth?, but do u know core of earth is always in motion ,it have ions or charge particle that why it generates magnetic field.

Earth magnetic field save us from harmful radiation which come from the space and sun.
it protect us from it.

hope it help