00:01
This question deals with an interference experiment.
00:04
I've drawn a diagram showing the fundamentals of the experiment right here.
00:09
This is a double slit experiment.
00:12
So we have two slits over here, and they're separated by distance d.
00:17
And then there is a distance from the slits to the screen where they're observed.
00:22
That's a distance l.
00:24
And then the x shows the distance from, say, the central maximum to the, one of the interference fringes there.
00:34
What we're trying to do in this experiment is to make our bright fringes appear farther apart.
00:39
So we want to make x bigger.
00:42
Now the basic equation that that holds in this double slit experiment is that d times the sine of theta is equal to m lambda, where m is an integer that tells us which interference fringe we're looking at the zero of order, i .e.
01:05
The central maximum, the first order interference fringe, et cetera.
01:10
D, as i said, is a separation between the two slits.
01:15
In the conditions that apply here in this particular experiment, we can use what's called the small angle approximations, and theta is going to be a pretty small angle.
01:25
In fact, that's the problem.
01:26
So we can say that the sign of the angle is equal to the tangent of the angle.
01:32
And the tangent of the tangent of the and the angle, as you can see for the diagram above, is equal to x divided by l.
01:38
So we have the equation d is equal to x divided by l is equal to m lambda.
01:45
Now, lambda is given to us trying to measure what that is, and we need to use all the good interference friends we can see.
01:51
So m, let's take it to be one.
01:55
And so we need to find some way of making x bigger.
01:59
Now let's look at what the possibilities are.
02:01
Move the laser closer to the slits.
02:04
Well, this formata doesn't have any part in it that talks about how close the laser is to the slits...