# Practice Quiz (Viva Questions)

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Viva Questions Determine the wavelength of the laser light by diffraction grating and demonstration.

1. What is full form of the LASER?

2. What is the condition for constructive interference?

3. How to find the grating element of a given diffraction grating having 1500 Lines Per Inch (LPI)?

4. What is the standard value of Red Color wavelength in He-Ne gas LASER?

5. What is grating Element?

6. What is diffraction?

7. What is Interference?

8. What is the formula for to find the percentage error?

Observed value=A

Standard value=B

1. $Error&space;=&space;\frac{A-B}{B}\times&space;100$
2. $Error&space;=&space;\frac{A-B}{A}\times&space;100$
3. $Error&space;=&space;\frac{A-B}{2B}\times&space;100$
4. $Error&space;=&space;\frac{2A-B}{B}\times&space;100$

9. What is spontaneous and stimulated emission process?

10. What is diffraction grating?

11. What are the Laser light characteristics ?

12. What is population Inversion?

13. Why do you use n lembda= d sin theta formula? What is the origin to derive this formula for this experiment?

14. Does diffracted Waves can interfere?

## Video Demonstration of the Experiment

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#### Dr Sushil Kumar

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