Answer:
(a) d = 1960nm
(b) The slit should be decreased.
(c) Δd = 360nm.
Explanation:
The double-slit interference is given by the following equation:
(1)
<em>where d: is the distance between slits, Θ: is the angle between the path of the light and the screen, m: is the order of the interference and λ: is the wavelength of the light. </em>
(a) To determine the least wavelength in the visible range in the third-order we need first to find the distance between slits, using equation (1) for a fourth-order:
Now, we can find the least wavelength in the visible range in the third-order:
So, the least wavelength in the visible range (400nm - 700nm) in the third-order is 653nm.
(b) To eliminate all of the visible light in the fourth-order maximum <u>means that the wavelength must be smaller than 400nm</u>, and hence the slit separation should be decreased <u>since they are proportional to each other</u> (see equation (1)).
(c) The distance between slits needed to eliminate all of the visible light in the fourth-order maximum, with λ = 400 nm as limit value, is:
Therefore the least change in separation needed is equal to the initial distance calculated for 490nm and the final distance calculated for 400nm:
I hope it helps you!
No. Sadly, you're not right. The whole problem here is the meaning of a few words. "Starts out"is the same thing as "initial" conditions. "At rest" is the same thing as not moving ... zero speed. So if an object starts out at rest, that says that its initial speed is zero ... choice 'b'.
X-rays and gamma rays are kept up there.
When I drive to the office, I drive through two school zones,
and four intersections that are controlled by traffic lights.
My average speed for the trip is higher than my instantaneous
speed is at any point in the school zones, or at any time when
I'm waiting for a red light to change.
Because the poles have like poles and like poles reple each other