Question

At most, how many bright fringes can be formed on one side of the central bright fringe (not counting the central bright fringe) when light of 625 nm falls on a double slit whose spacing is

		11
		9
		12
		10
		8

Answer 1

10 is the correct answer.

here is the expalnation

let n is is the maximum no of bright fringes formed.

for bright fringes, the path diffrence, d*sin(theta) = n*lamda (here d is silt separation and lamda is wavelelgnt)

for nth(maximum bright fringes) sin(theta) = sin(90)

so, d = n*lamda

n = d/lamda

= 6.77*10^-6/(625*10^-9)

= 10.8

here n should be integer.

so the answer is 10