What causes Earth to have a magnetic field? What will be an ...

[naturalchemist]

What causes Earth to have a magnetic field?
 
  What will be an ideal response?

Question 2

Describe the effects of thermal expansion, conduction of heat, and viscosity on the determination of whether heat transfers through material by conduction or convection.
 
  What will be an ideal response?

[yasmina]

Answer to Question 1

The motion of molten iron in the outer core produces an electrical current and this current generates a magnetic field.

Answer to Question 2

Thermal expansion is an increase in volume with the addition of heat. A substance that has a large increase in volume with the addition of heat is a good substance to undergo convection. Conduction of heat is the transfer of heat through a substance by molecular motion. In order for a substance to be a good convector of heat, that substance should be a poor conductor of heat. Viscosity is the resistance to flow. A good convector of heat will not be very resistant to flow (low viscosity). The significant thermal expansion and very, very low heat conductivity would favor convection but not enough to overcome the extremely high viscosity, so convection does not occur except locally in magma chambers.

[naturalchemist]

Excellent

[amcvicar]

TYSM