In young’s double-slit experiment using monochromatic light, the interference pattern consists of a central

In Young’s double-slit experiment using monochromatic light, the interference pattern consists of a central MAXIMUM.

Explanation:

In Young's double slit method of experiment we know that on the screen we have light of monochromatic source.

Due to this double slit system when light reaches to the screen there exist a finite path difference on the screen and which will create phase difference between two light reaches on the screen

It is given as

(Path difference)

so here if path difference is zero due to two slits at the center of the screen

Then in that case

so we will have maximum intensity at the center of the screen when light will reach at the center of the screen.

the box does not move because you need to use a force greater than 300 n. you are only using 50 n. it needs to at least be 301 n for the box to move because then it is an unbalanced force and it will move the way that the greater force is pushing it. if you use only 300 n it will be a balanced force and will not move because the force you are exerting on the   box is the same as its force.

hope this !

im sorry if i went too in depth, i am going to include a link to a video on khan academy that will explain this.   hope that you like the video and that it explains more in detail to you.

that is the link.