Question: Q. 15. A cell of emf ’ ’ and internal resistance ’ ’ is connected across a variable load resistor . Draw the plots of the terminal voltage versus (i) and (ii) the current .
It is found that when , the current is when is increased to , the current reduces to . Find the values of the emf and internal resistance .
A [Delhi I, II, III 2015]
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Solution:
Ans. (i)

(ii)


…(i)
From equation (i) and (ii),
2
Using this value of , we get
[CBSE Marking Scheme 2015]
Detailed Answer :

From (1) & (2)
the pots are:


