An LC circuit like the one shown in the figure contains a 95

An LC circuit like the one shown in the figure contains a 95.0 mH inductor and a 15.0 µF capacitor that initially carries a 160 µC charge. The switch is open for t < 0 and then closed at t = 0. (a) Find the frequency (in hertz) of the resulting oscillations. 133.3 Correct: Your answer is correct. Hz

(b) At t = 1.00 ms, find the charge on the capacitor. 159.9 Incorrect: Your answer is incorrect. Your response differs from the correct answer by more than 10%. Double check your calculations. I redid the problem 3x and i keep getting the same answer

µC (c) At t = 1.00 ms, what is the current in the circuit? -1.95 Incorrect: Your answer is incorrect. Again, i dont know how this could be wrong

Solution

a)

f = (1/sqrt(LC))/(2*pi)

As you have got the correct answer i have left this part.

b)

Charge on the capacitor is given by :

Q = Qo*cos(2*pi*f*t)

where Qo = 160 uC

So, at t = 1 ms,

Q = 160*cos(2*pi*133.3*1*10^-3)

= 107.1 uC <-------answer

c)

Current in the circuit is given by :

I = Io*sin(2*pi*f*t)

where Io = Qo/(2*pi*f)

= (160/(2*pi*133.3))*sin(2*pi*133.3*1*10^-3)

= 0.142 A