Which of the following statements is true about magnetic fields.
The earth's magnetic field is confined within the core of the earth.
Magnetic fields are unreliable for use in navigation.
Magnets and magnetic fields were only just discovered in the last 500 years.
The earth's magnetic field protects the surface from strong electrical currents coming from the sun.

The earth's magnetic field protects the surface from strong electrical currents coming from the sun

Explanation:

The Earth's magnetic field called the “magnetosphere” – protects our atmosphere from the “solar wind.” That's the constant stream of charged particles flowing outward from the sun. When the magnetosphere shields the Earth from these solar particles, they get funneled toward the polar regions of our atmosphere.

The Earth's magnetic field serves to deflect most of the solar wind, whose charged particles would otherwise strip away the ozone layer that  protects  the Earth from harmful ultraviolet radiation. One stripping mechanism  is  for gas to be caught in bubbles of magnetic field, which are ripped off by solar winds.

the answer is b, have negligible mass

find the surface area of the sphere to the nearest square unit. use a calculator.

a. 254 in.2

b. 64 in.2

c. 127 in.2

d. 1,018 in.2