Objective:
-To show that laser light hitting a double slit creates a pattern due to a combination of single-slit diffraction and interference
-To demonstrate that the spacing of interference and diffraction fringes depends on the wavelength of light (green light has a smaller wavelength, and thus would have narrower fringes)
Apparatus:
- Red laser pointer
- Green laser pointer
- box of grating slides
- light stand and 3 finger clamp for laser pointer
- lens holder and screen from optical bench setup
Method:
Point the red laser pointer at the slits in the middle of the “multiple slit (2)” slide. Project the laser light that passes through the slits onto the screen. Observe that there are regular dark bands in the light, along with a broader overall light-dark pattern due to diffraction. Changes can now be made to the setup and the effect on the pattern observed, such as: replacing the double slit with a single slit or a six-slit mask; replacing the red laser with a green laser; changing the position of the screen.
Notes: