The magnetic lines of force are closer at the poles as the result the force is stronger at the poles but when they are away from the poles, the force is comparatively less strong.

From the formula of resistance, we have,

Resistance = Resisitivity * Length / Area

So, the resistance depends upon the following factors:

i) Resistivity of the material, which in turn is dependent upon the nature of the material and temperature

ii) Length of the material

iii) Cross sectional area of the material

The angle of dip in the magnetic south pole of the earth is 90 degree because the needle remains vertically at the poles.

Ammeter is the device used to measure the electric current. So, total current flowing through the circuit must pass through the ammeter. Therefore, it is connected in series. While voltmeter is the device used to measure the potential difference between two ends. Therefore, voltmeter is parallel to measure the potential difference across two ends.