# 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 diffraction?

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

3. What is population Inversion?

4. What is spontaneous and stimulated emission process?

5. Does diffracted Waves can interfere?

6. What is full form of the LASER?

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

8. What is grating Element?

9. What are the Laser light characteristics ?

10. What is the condition for constructive interference?

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

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

13. What is Interference?

14. What is diffraction grating?