Question

In young's double slit experiment how many maximas can be obtained on a screen (including the central maxima) if l = 2000 Å and d = 7000 Å ?

• A. 12
• B. 7
• C. 18
• D. 6

Answer 1

Answer: (B)

7

Answer 2

For maxima,

Dx = d sin q = nl

\ sin q = $\frac{n\lambda}{d} = \frac{n \times 2000}{7000}$

Since sinq cannot be greater than 1.

\ n = 0, 1, 2, 3 only

\ 3 maxima on both side of screen and 1 central maxima will be obtained.

\ Total maxima = 7