I really need help with this one, Can someone please solve the following problem

Question

I really need help with this one, Can someone please solve the following problem, showing and explaing all steps so that I can see where I have gone wrong? I will award all points to the most complete and thorough answer. Thank you for your help!!!

in the circuit shown below, C = 5.90pF, E = 23.0v, R = 450ohm and the emf negligible Internal resistance. Initially the capacitor is uncharged and the switch S in the position X. The switch is then moved to position 2. so that that the capacitor begins to charge. Switch S in position 1 switch s in position 2 immediately after the switch s, moved to position 2, what is the current through the resistor? After the switch is in position 2 for 4.00 ms, what it the charge on the capacitor? After the capacitor fuly charged, the switch Is moved back to position 1. How long does it take the charge on the capacitor to reach one half of its maximum value?

Explanation / Answer

a) capacitor is uncharged so V resistor = V

V = IR
I = V/R = 28/450=0.0622 A

b) Q = Qmax (1 - e^(-t/tau))
Qmax = CV and tau = RC
= 5.9E-6*28*(1 - e^(-4.0E-3/(450*5.9E-6)))=1.29E-4 C

c)

now will decay
Q = Qmax e^(-t/tau)

1/2 = e^(-t/tau)

t= -tau ln(1/2) = 450*5.9E-6*ln(2)= 1.84E-3 s

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