00:01
Now this question, you have a particle, you have a spin half particle, and it's supposed to be in the following state, side equals half this and plus square of three over two, a half down, right? and you see that this state is normalized, right? because if you are squared this and square this, you put them together, it's the exact one.
00:20
So this is normalized the state.
00:24
And these two states plus up and down are the eigen states of the z components of the d component to angular, the spin operator, right, sd.
00:36
And then you asked what is mean values of sd and x in this state? well, the mean value of sg in this state is simply given by sd side just to the average, right? and this is given by, because this angle state, again state is easy to see that is 1 over 4 times.
00:56
The upstate has a value which is h bar over 2, right? and plus this data has a probability 3 over 4 and has a value means h by over 2, right? so you would get just, you will get obviously it's h times this minus half, right? so it's minus h5 .4.
01:20
So that's the average value of this is here.
01:22
But how about the average value of the x, right? so if you do the same, just do xx, now many ways to do this, way to do this actually i would like to use a simple way to do it.
01:38
You know, i want to use, i want to turn this into matrix form, right? i want to turn this actually into kind of matrix form.
01:45
So what i would do is to, but of course you can also make use of the hand in the question.
01:54
That is you, okay, let me use the hand in the question that is giving, i want x using the raising and low lurang operators, right? so you can write it as si and then s plus and plus as minus, right? and then side, right? so that would be it...