Question

name a device which helps to maintain potential difference across a conductor(say,a bulb).

Answer 1

Ans: An electric cell or a battery helps to maintain a potential difference across a conductor.

Hope it helps...!!

Answer 2

Name a device by which we measure the potential difference across a conductor :-

Voltmeter is an instrument used fro measuring the electric potential difference between two end of conductor. Voltmeter should have high resistance as it does not draw current going through circuit. Now a days we have Multi meters which are used to measure current, potential difference and resistance.