In a Young's double-slit experiment, if the distance between the two slits is doubled () and the distance to the screen is halved (), by what factor does the fringe width change?

Answer and explanation

Correct answer: A. It becomes of the original value

  1. Step 1: The fringe width is given by .
  2. Step 2: Substitute the new parameters: and .
  3. Step 3: Compute: . The fringe width is reduced to one-fourth of its initial value.
Answer
It becomes of the original value.
Why not the others: Remaining unchanged would require and to change in the same proportion; Doubling inverts the scaling; Quadrupling assumes doubles and halves.

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