The central maximum of a single slit has width 3600 when vie

The central maximum of a single slit has width 3600 when viewed on a screen 0.80 m behind the slit.

How wide (in mm) is the slit?

for single slit experiment:

sin A = lambda/b

b = 3600*lambda

sin A = 1/3600

A = arcsin (1/3600) = 2.78*10^-4 deg

slit width will be 2*y, also

y/a = tan A = sin A = A (for small angle)

y/0.80 = A

y = 0.8*2.78*10^-4 = 2.224*10^-4 m

slit width = 2*y = 4.448*10^-4 m

slit width = 0.4448*10^-3 m = 0.445 mm