Question 645: Current Electricity

Question

A 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

Accepted Answer

Current in the circuit, $$I = {\varepsilon  \over {R + r}}$$
Potential difference across R,
$$V = IR = \left( {{\varepsilon  \over {R + r}}} ight)R$$
$$V = {\varepsilon  \over {1 + {r \over R}}}$$
When R = 0, V = 0  and when  R = $$\infty $$, V = $$\varepsilon $$
$$ 	herefore $$ option (c) represents the correct graph.

Answer

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Answer

Current Electricity

A 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

Choose the correct answer: