The time taken for the capacitor voltage to be 45 % of the battery voltage is 5,750.3 s.
The rate at which the capacitor voltage discharges is given by the following formula;
[tex]V = V_0(1 - e^{-t/RC})[/tex]
Where;
The final voltage = 0.45 x 5 V = 2.25 V
[tex]2.25 = 5(1 - e^{-t/RC})\\\\(1 - e^{-t/RC}) = \frac{2.25}{5} \\\\(1 - e^{-t/RC}) = 0.45\\\\e^{-t/RC} = 1- 0.45\\\\e^{-t/RC} = 0.55\\\\\frac{-t}{RC} = ln(0.55)\\\\\frac{-t}{RC} = -0.597\\\\t = 0.597 (RC)\\\\t = 0.597(3440 \times 2.8)\\\\t = 5,750.3 \ s[/tex]
Thus, the time taken for the capacitor voltage to be 45 % of the battery voltage is 5,750.3 s.
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