can some1 explain to me how double-slit and interference are related? what is double slit????

Answer 1

double slit is where light hits two slits separated by a small distance. Beyond the slits, the two slits look like two light sources in phase with each other. Thus you get interference between the two sources. When the path length from both slits to a target beyond is the same for both (straight ahead) or differs by an integral number of wavelengths, the two sources reinforce each other and you see a bright stripe. Then they differ by an odd number of half wavelengths, the two sources interfere destructively and you get a dark stripe.

Answer 2

thank you so much!!!