Light can be transmitted through long fiber optic strands because of question 17 options: interference. external diffraction. refraction. total internal reflection.

light can transmitted through long fiber optic strand as a result of total internal reflection

Explanation:

Total internal reflection occur when a right ray incident at the interface of two less dense media is completely reflected back to a denser medium, as a result of a greater angle than the critical angle.

Optical fibers use total internal reflection to transmit light. Light passing through the inner core of the optical fiber strand is reflected back rather than being refracted to the cladding.

Note: the optic fiber is made of dense solid glass core (the inner) surrounded by less dense cladding (outer)

come closer and become far apart and become steam/gas

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.