Physics 3.2.1-2 Interference and Diffraction

25 flashcards · Physics · by TheoTyson

1. What does monochromatic mean?

   The light all has the same wavelength.

2. How are light diffraction patterns demonstrated with a laser?

   If the wavelength of light is similar to the aperture then a diffraction pattern will be displayed that has a central bright fringe, and alternating light and dark fringes.

3. When are two sources coherent?

   If they have the same wavelength, frequency and a fixed phase difference between them.

4. What is the path difference of two waves?

   The extra distance one wave has travelled compared to the other.

5. At what path difference does constructive interference occur?

   When the path difference is a scalar multiple of the wavelength.

6. At what path difference does deconstructive interference occur?

   When the path difference is a scalar multiple of half a wavelength out, but not a whole wavelength.

7. What is diffraction?

   As waves pass through a narrow gap, they spread out.

8. What happens if the gap of diffraction is a lot bigger than the wavelength?

   The diffraction is unnoticeable.

9. When does the most diffraction occur?

   When the gap is the same size as the wavelength.

10. What happens if the gap of diffraction is a lot smaller than the wavelength?

    The waves are mostly just reflected back.

11. What must the light be for clear interference patterns to be observed?

    The light must be coherent.

12. What happens when white light is diffracted?

    All of the different wavelengths are diffracted by different amounts, a spectra of colours produce fringe patterns.

13. What does an increase in the intensity of light mean?

    There is an increase in the number of photons per second.

14. What is the effect of increasing the slit width?

    Decreases the amount of diffraction, the central maximum is narrower, and the intensity is higher.

15. What is the effect of decreasing the slit width?

    Increases the amount of diffraction, the central maximum is wider, and the intensity is lower.

16. What kind of light does a laser produce?

    Coherent and monochromatic light.

17. What happens when a laser light is passed through a double slit?

    Produces a diffraction pattern with dark and light fringes.

18. What are some safety precautions for lasers?

    Do not aim at a person. Wear laser goggles. Have a warning sign on display.

19. What is the formula for fringe spacing?

    w=λDsw = \frac{\lambda D}{s}w=sλD​ (w) fringe spacing(w) \, \text{fringe spacing}(w)fringe spacing (D) distance to screen(D) \, \text{distance to screen}(D)distance to screen (s) space between slits(s) \, \text{space between slits}(s)space between slits

20. What is Young's double slit evidence for?

    Electromagnetic radiation being a wave as interference patterns were produced.

21. What is the formula for a diffraction grating?

    dsin⁡θ=nλd \sin{\theta} = n \lambdadsinθ=nλ (d) distance between slits(d) \, \text{distance between slits}(d)distance between slits (n) order of fringe(n) \, \text{order of fringe}(n)order of fringe

22. What is the effect on the diffraction patter when increasing the wavelength?

    The pattern will spread out more.

23. What is the effect on the diffraction pattern when increasing the distance between the slits?

    The pattern will spread out less.

24. What is the first order line?

    The line with the maximum brightness in the centre.

25. What does a diffraction grating of white light look like?