Question

A single slit is 20.0 um wide, and illuminated by yellow 500 nm light. A screen is 2.0 m away. How
far from the midline of the screen is the first minimum, in mm?

Answer 1

In interfreence or diffraction pattern,

the needed equation is Y = mLR/d---------------1

and d sin theta = mL--------------------2

where L = wavelgnth,

m = order = 1,2,3,4, ......... for brigth bands

m = 1.5, 2.5, 3.5, 4.5, ......for dark bands

R is the distance from slit to screen,

Y = disatnce from central spot to nth order fringe

so here apply Y = (1+0.5) * 500 e-9 * 2/(20 e-6)

Y = 75 mm--------------------<<<<<<<<<<< is the   answer