Question

There are two sources kept at distances 2λ apart. A large screen is perpendicular to the line joining the sources. Number of maxima on the screen in this case (λ= wavelength of light) is 

• A. 1
• B. 3
• C. 5
• D. 7

Hint:

If source separation is d=nλ, total maxima on a perpendicular screen are: 2n+1

Answer 1

The Correct Option is C

Step 1: Separation between sources: d = 2λ 
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Step 2: Condition for maxima: Δ = nλ. Maximum possible path difference: Deltamax = d = 2λ 

Step 3: Possible values of n: n = -2, -1, 0, 1, 2 

Step 4: Total number of maxima: 2nmax+1 = 2(2)+1 = 5