Diffraction can be easily observed using a laser beam because lasers produce coherent, monochromatic (single-wavelength), and well-collimated light — ideal conditions for clear diffraction patterns. Here’s how you can observe diffraction with a laser:
How to Observe Diffraction Using a Laser Beam:
- Setup:
- Shine a laser beam onto a narrow slit, a thin wire, or any small obstacle.
- Place a screen some distance behind the slit or obstacle to observe the light pattern.
- Diffraction Pattern Formation:
- As the laser light passes through the slit or bends around the obstacle, it spreads out due to diffraction.
- On the screen, you will see a pattern of bright and dark fringes (bands), which are caused by constructive and destructive interference of the diffracted light waves.
- Types of Diffraction Patterns:
- Single slit: A central bright fringe with progressively dimmer fringes on either side.
- Double slit: A series of equally spaced bright and dark fringes (interference pattern).
- Diffraction grating or multiple slits: More complex and sharper fringe patterns.
- Varying the Slit Width:
- By changing the slit width, you can see the diffraction pattern change—narrower slit results in wider fringes.
- Practical Note:
- Make sure the room is dim for clear visibility of the fringes.