Demo Title: Transmitting Sound with Lasers
Demo overview:
This activity demonstrates the ability to transmit information using light! In order to demonstrate this we will be using an ordinary laser pointer connected to a sound-source (such as an iPad’s headphone jack). We will also be using a photodetector (such as a solar panel) connected to external speakers.
Steps:
- Connect the photodetector to a power source and speaker
- Connect the laser to an iPad or some other device with a headphone jack that audio can be played from
- Ensure that the laser is pointed at the photodetector
- Turn on the laser. NOTE: When not actively doing the demo, make sure that the laser is off to reduce risk of eye injuries!
- Observe the flat tone being transmitted from the laser to the photodetector and output through the speakers.
- Select audio from the iPad or similar device to be played
- Have fun!
Questions to ask the class:
- What applications does this kind of technology have in the real world?
- Satellites, communication, etc.
- What do you think will happen if we place a vibrating tuning fork in front of the laser while it is on?
- Buzzing sound from the tuning fork interfering with the laser’s path
- What do you think would happen if we used a different colored laser?
- This depends on the wavelength that the photodetector is most sensitive to.
Outreach Commentary: Wonders of Physics Outreach Fellowship Experiences
Prior to attending the University of Wisconsin–Madison, I had only performed outreach as a member of my undergraduate university’s Society of Physics Students chapter and the Planetarium. While there I participated in activities such as physics demonstrations at the annual Oceana Airshow, regular planetarium shows, and leading girl scout troops in obtaining their space explorer badges. While at the University of Wisconsin–Madison, the Wonders of Physics Outreach Fellowship has given me the opportunity to explore my already-established passion for outreach and science learning. I led students in IceCube Afterschool, an annual afterschool program for highschool students to learn more about the IceCube collaboration and obtain sought-after skills such as programming and hardware. For this outreach activity, I led a group of three high school students in the development and implementation of software using Arduino to make a mode of the IceCube detector. This software interfaced with LED lights and speakers to produce tracks and cascade events depending on the type of neutrino the model “detected.” In addition to this, I participated in the annual Wonders of Physics show where I performed a fast-paced and exciting new demonstration: Transmitting Sounds with Lasers. In this activity, dressed as an astronaut whose favorite number is c (the speed of light), I used a laser pointer to transmit music from my “space datapad” (iPad) to a photodetector across the room. This photodetector was connected to the room’s speakers and interpreted the light as a signal that the speakers could output as sound! Overall, I enjoyed the fellowship very much and look forward to participating in the Wonders of Physics show again next year!