Grades: 6 to 12
Duration: 1/2 Hour – 1 Hour
NGSS Connections PS4 Waves and their applications in technologies for information transfer
- Digitized information can be transmitted over long distances without significant degradation. High-tech devices, such as computers or cell phones, can receive and decode information – convert it from digitized form to voice and vice versa. (4-PS4-3)
- The path that light travels can be traced as straight lines, except at surfaces between different transparent materials (e.g. air and water, air and glass) where the light path bends. (MS-PS4-2)
- Multiple technologies based on the understanding of waves and their interactions with matter are part of everyday experiences in the modern world (e.g. medical imaging, communications, scanners) and in scientific research. They are essential tools for producing, transmitting and capturing signals and for storing and interpreting the information contained in them (HS-PS4-5)
Supplies: Laser Pointer or Laser Blox, Lumi Rod
Explore Total Internal Reflection
If you look at the right angle, a transparent angle can reflect light better than any mirror. To observe the phenomenon, point the laser into the acrylic block so that it enter s at an angle. Adjust the angle until you notice that the beam no longer passes through the block, but reflects off the inner edge just like in the image.
Find the Critical Angle
Using a protractor to measure the incident and reflected angels, find the angle at which no beam is transmitted and nearly 100% of the beam is reflected,. This is the Critical Angle.
Observe Light Transmission
Total internal reflection helps transmit telecommunications data along optical fiber s. Any light that is not aligned parallel to the axis of the fiber hits the wall of the fiber and is reflected (totally!) back inward, since the angle of incidence with which the light hits the wall is much larger than the critical angle . This prevents the signal from weakening as it travels a long distance.