00:01
Well, this is asking us about resonant frequency.
00:06
And i know omega -0, which is the resonant angular frequency, is the square root of 1 over lc.
00:16
We're told that r is 20 oms, l is 0 .0020 henry.
00:29
C is 4 times 10 to the negative 6th ferret.
00:40
So also omega is 2 pi f sub 0.
00:48
And so f is going to be 1 over 2 pi pi times the square root of 1 over l .c.
00:58
So let me put that in a calculator.
01:00
1 over 2 pi times 1, the square root of 1 over l, which is 0 .002, c, which is 4 times 10, to the negative 6th power.
01:24
Rounding that to two significant digits, it's 1 ,800 hertz.
01:31
B, the impedance of the circuit is the square root of r squared, plus omega l squared minus, no, i didn't get that right, sorry, just omega -l minus 1 over, whoops, one over omega -c squared.
02:11
Now, we do need to know omega, omega, omega, omega, omega is just going to be 1 over the square root of l -c, or the square root of l -c, or the square root of 1 over l -1 -l -0.
02:24
C...