# Interferometer - Mechanical Engineering (MCQ) questions and answers

1)   What does N, P and L mean in N.P.L. Gauge interferometer?

a. Nikon pulsed laser
b. Nuclear plasma laboratory
c. National Physics Laboratory
d. Nuclear physics laboratory
 Answer  Explanation ANSWER: National Physics Laboratory Explanation: No explanation is available for this question!

2)   Which type of fringe is formed, if a path difference of  λ/2 is observed in an interference pattern?

a. Dark fringe
b. Bright fringe
c. Both bright and dark fringe overlap
d. Unpredictable
 Answer  Explanation ANSWER: Dark fringe Explanation: No explanation is available for this question!

3)   At which angle does a glass plate reflector set in N.P.L. interferometer?

a. 30o
b. 45o
c. 60o
d. 90o
 Answer  Explanation ANSWER: 45o Explanation: No explanation is available for this question!

4)   A surface of 2.1 mm is to be measured using a interferometer. Calculate nominal fraction for blue light which has wavelength of 0.785 μm.

a. 0.8280
b. 0.5350
c. 0.3185
d. 0.1910
 Answer  Explanation ANSWER: 0.3185 Explanation: No explanation is available for this question!

5)   An interferometer is used to measure a surface of 1.85 mm. Calculate number of fringes, when λ = 0.659 μm.

a. 5614.567
b. 5000.236
c. 2807.283
d. None of the above
 Answer  Explanation ANSWER: 5614.567 Explanation: No explanation is available for this question!

6)   Which type of surface, has a fringe pattern shown below? a. Sphere
b. Cylinder
c. Conical
d. Spheroid
 Answer  Explanation ANSWER: Spheroid Explanation: No explanation is available for this question!

7)   Which among the following is used to create fringes in N.P.L. interferometer?

a. Condensing lens
b. Collimating lens
c. Optical flat
d. All of the above
 Answer  Explanation ANSWER: Optical flat Explanation: No explanation is available for this question!

8)   Which type of light source is used in N.P.L. type of flatness interferometer?

a. Mercury vapour lamp
c. Both a. and b.
d. None of the above
 Answer  Explanation ANSWER: Mercury vapour lamp Explanation: No explanation is available for this question!

9)   Which type of surface in a fringe pattern exhibits the movement of fringes towards the centre?

a. concave surface
b. convex surface

 Answer  Explanation ANSWER: concave surface Explanation: No explanation is available for this question!

10)   What does the following interference band pattern indicate? a. Gauge has taper along its large edge
b. Gauge has taper along its short corner
c. Flat gauge
d. Bands have same direction but the pitch is different
 Answer  Explanation ANSWER: Gauge has taper along its short corner Explanation: No explanation is available for this question!

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