Physics · Interference: Young's double-slit experiment and expression for fringe width, coherent sources and sustained interference of light

If yellow light emitted by sodium lamp in Young's double slit experiment is repl

If yellow light emitted by sodium lamp in Young's double slit experiment is replaced by monochromatic blue light of same intensity keeping other parameters constant the new fringe width will :

  • A. Remain unchanged
  • B. Increase
  • C. Decrease
  • D. Can't be predicted

Step-by-step solution

Fringe width in Young's double slit experiment is given by β = λD/d, where λ is the wavelength, D is the distance to the screen, and d is the slit separation. Blue light has a shorter wavelength than yellow light. Since other parameters remain constant, a decrease in λ leads to a decrease in fringe width.
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