Current Electricity - Result Question 41

43. Cell having an emf $\varepsilon$ and internal resistance $r$ is connected across a variable external resistance $R$. As the resistance $R$ is increased, the plot of potential difference $V$ across $R$ is given by :

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(c)

(d)

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Answer:

Correct Answer: 43. (c)

Solution:

  1. (c) The current through the resistance $R$

$I=(\frac{\varepsilon}{R+r})$

The potential difference across $R$

$V=I R=(\frac{\varepsilon}{R+r}) R$

Thus $V$ increases as $R$ increases upto certain limit, but it does not increase further.