current-electricity Question 49
Question: Q. 2. Two cells of emf’s approximately
(a) The battery that runs the potentiometer should have voltage of
(b) The battery of potentiometer can have a voltage of
(c) The first portion of
(d) Potentioneter is usually used for comparing resistances and not voltages.
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Solution:
Ans. Correct option : (b)
Explanation: Given that,
emf of primary cells are
The potential drop across potentiometer wire must be slightly more than that larger emf
So, the battery should be of
Very Short Answer Type Question
(1 marks)
[AI Q. 1. Why is potentiometer preferred over a voltmeter for determining the emf of a cell?
] [Delhi Comptt., 2016]
Ans. Potentiometer does not draw any (net) current from the cell. Voltmeter draws some current from cell, when connected across it, hence it measures terminal voltage.
[CBSE Marking Scheme, 2016] Detailed Answer :
Potentiometer is preferred over voltmeter because voltmeter needs a current to pass through it so as to measure the potential difference. The potential difference being measured by the voltmeter is given as
