00:01
So in this lc circuit, we already know that at t equal to zero, the charge on the capacitor q equal q not, and it is maximized.
00:15
So the energy at t equal to zero is 1 over 2c times q0 squared, right? so this is the energy stored in the capacitor, and it is also the energy stored in the circuit.
00:28
So we want to find out the moment where the, when the energy is halved.
00:34
So basically half e equal 1 over 4c times q0 squared.
00:40
So it equal 2c times q squared.
00:44
So q here is the one that we need to find out.
00:49
So q, just do the very simple math.
00:52
You can see that q equal to q0, q0 over square 2, right? so when the charge on the capacity becomes q0 over square 2, then the energy on the capacity is the same as the energy on the inductor.
01:10
And for the lc circuit, we also know the expression q equal q0, cosine, cosine, plus 5, right? so omega here is the resonance frequency, where omega equal 1 over square root lc, right? and we already know that when t equal to 0, q is maximized.
01:37
So 5 here simply equal to 0.
01:40
So we can simplify the expression for the q as q equal q0 times cosine omega -t...