A cell having an emf ε and internal resistance r is connected across a variable external resistance R. As R is increased, the plot of potential difference V across R is given by: [Diagram: Image]
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A cell having an emf ε and internal resistance r is connected across a variable external resistance R. As R is increased, the plot of potential difference V across R is given by: [Diagram: Image]

G1 Physics · Accepted Answer

Step 1: I = ε/(R+r). Step 2: Terminal voltage V = IR = εR/(R+r). Step 3: V(0)=0, dV/dR >0, and as R→∞, V approaches ε asymptotically. Thus choose the increasing saturating curve.