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Question:

Three identical capacitors A, B and C are charged to the same potential and then made to discharge through three resistances RA > RB > RC. Their potential differences (V) are plotted against time t, giving the curves 1, 2 and 3. Choose the incorrect option. 1→A, 2→B, 1→C, 3→A

1→A

3→A

2→B

1→C

Solution:

In case of discharging of capacitor we have the voltage formula as: V = V0e^[−t/RC]
Now the higher value of R will make it more concave so in the given figure 1 is least concave so it has to be wrong. Concavity is tested by checking the slope of the graph.