Metrology and Quality Control - Mechanical Engineering (MCQ) questions and answers for Q. 4803

Q.  Which type of fringe is formed, if a path difference of  λ/2 is observed in an interference pattern?
- Published on 07 Aug 15

a. Dark fringe
b. Bright fringe
c. Both bright and dark fringe overlap
d. Unpredictable

ANSWER: Dark fringe


  • MANIMARAN.J   -Posted on 12 Sep 17
    the page results updated
  • Sravanthi   -Posted on 26 Oct 15
    - When a monochromatic light strikes an optically flat surface, then it is divided into two parts.

    - The reflected rays obtained may be in phase or out of phase.

    - If the path difference is an odd number of half wavelength, interference occurs and a dark fringe is obtained.

    - Let h be the air gap between bottom of the optical flat and the test surface. If h = λ/4 and the path difference is equal to λ/2, then the beams are out of phase and a dark fringe is obtained.

    - When h = λ/2, the beams are in phase and bright fringe is obtained. λ/2 is the distance between two dark fringes.

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