Thames & Kosmos 665050, Руководство по эксперименту

Страница: 37 / 52

For centuries, it was a complete mystery why a magnetic needle
pointed to the north or south. Scientists rightly asked what the
rotation of Earth might have to do with magnetism. Were there,
for example, gigantic magnetic mountains at Earth’s poles? Or
might the North Star, which could be seen above the North Pole,
be responsible?
Today we know that Earth acts as if there were a giant bar magnet
hidden inside it. But Earth’s magnetic poles don’t exactly match the
rotational poles. Instead, they are a few thousand kilometers away. Between these
magnetic poles, there is a powerful magnetic field stretching across the entire globe.
This is what your magnets and all magnetic compasses react to. Earth’s magnetic field
isn’t actually produced by a permanent magnet, but by enormous electric currents
circulating deep beneath the surface in its metallic core.
MAGNETIC MOUNTAINS C
In fact, you can’t detect any
particularly strong magnetic field at Earth’s magnetic poles. And there’s
nothing very unusual about the landscape there. The supposed
magnetic mountains — in the Middle Ages, people believed in the
existence of a magnetic mountain that could pull the iron nails out of
ships that passed by it — belong to the realm of fairy tales. What is
interesting is that the magnetic field’s lines of force enter the magnetic
poles in a vertical direction, so the needle of an appropriately designed
compass will point straight down.
EARTH’S MAGNETIC FIELD
CHECK IT OUT
✔
Magnetic Force and Magnetic Fields |
35