Answer:
655128 ohm
Explanation:
C = Capacitance of the capacitor = 7.8 x 10⁻⁶ F
V₀ = Voltage of the battery = 9 Volts
V = Potential difference across the battery after time "t" = 4.20 Volts
t = time interval = 3.21 sec
T = Time constant
R = resistance
Potential difference across the battery after time "t" is given as
[tex]V = V_{o} (1-e^{\frac{-t}{T}})[/tex]
[tex]4.20 = 9 (1-e^{\frac{-3.21}{T}})[/tex]
T = 5.11 sec
Time constant is given as
T = RC
5.11 = (7.8 x 10⁻⁶) R
R = 655128 ohm
