What is electricity speed?

Electromagnetic induction. a coil of wire contains n turns and has an electrical resistance r. the radius of each turn is a. initially, inside the coil there exists a uniform magnetic field of magnitude b0 parallel to the axis of the coil. the magnetic field is then reduced slowly. the current induced in the coil is i. how long does it take for the magnitude of the uniform field to drop to zero?

4. if you were an astronaut on the moon, what would you experience? what would you see from your perspective?

Does the earth behave like a magnet how do you prove it