Maximum power by battery and potential gradient

Define potential gradient.

The unit of potential gradient is

A potentiometer wire has resistance 40Omega and its length is 10m. It is connected by a resistance of 760Omega in series if emf of battery is 2V then potential gradient is:-

For maximum power from battery the internal resistance of battery r is

S.I. unit of potential gradient is

In potentiometer the potential gradient is –

A potentiometer wire 10 m long has a resistance 40ohms. It is put in series to a resistance 760ohms and connected to a 2volt battery. The potential gradient in the wire is –

Establish relation between electric field and potential gradient. Or Derive relationship between Electric field intensity and potential gradient at a point in the electric field.