Interference

• Speed of light laser apparatus (should already be mounted in the room)
• Mirror (should already be mounted in the room)
• Oscilloscope
• 2 BNC cables
• 1 50-ohm terminator
• Flexible tape measure
• 2 C-clamps
• 2 metal rulers

Setup:

• Plug in the apparatus. Connect the detector output to Channel 1 of the scope (using the 50-ohm terminator) and connect the TTL output pulse from the detector to External Trigger of the scope.
• Adjust the position of the apparatus so that beam hits mirror at the other end of the reagent shelf. (Device may need to turned side-to-side or adjusted up-down).
• Check (or adjust) the beam splitter to ensure that the “initial” beam is deflected into the photoreceiver.
• Check (or adjust) the mirror at the far end of the bench to ensure that the “reflected” beam is sent back into the beam splitter (and then onto the photoreceiver). This will require the most iteration.
  • Look at the initial and reflected signals on the scope at the same time.
  • Adjust the mirror to maximize the size of the reflected signal.

• Microwave transmitter (and plug)
• Microwave receiver (and plug)
• 90-degree microwave track
• Adjustable angle microwave track
• 2 reflectors
• 2 reflector holders
• 1 beam splitter
• 1 beam splitter holder
• Wood shim and C-clamp
• Meter stick

You do not need to assemble the interferometer. Students will use the raw components in different ways in their experiment and are expected to build as needed.

Individual station:

• Optical rail
  • 3 post holders
  • Sound level meter
  • 2 speakers
  • 1 short speaker holder
  • 1 long speaker holder (if a long holder isn't available, use another short one)
• 2 BK function generators (unmodified, if available)
  • 1 BNC to double-banana adapter
• Oscilloscope
  • 2 long BNC cables (to connect to sound level meter and to connect to TTL output of function generator)
• Beats box
  • 1 pair of headphones (include a second pair, if available)
  • 4 BNC cables
• 1 tuning fork (include a second different fork, if available)
• Meter stick

Setup:

• Test the relative intensities of the two speakers and try to find a pair comparable ones. The best “match” is one where the destructive interference (at several kHz) is close to zero and the constructive interference is large and distinct.

“Mystery signal”:

• BK function generator (modified is OK) placed at the end of the island bench and/or on the outer bench (as needed)

Setup:

• Connect the generator to one of the BNC jacks on the “central line” running along the island bench or along the outer perimeter.
• Set the frequency to a few kHZ.
• Adjust the amplitude down to the minimum value (turned fully counter-clockwise and attenuator pulled out) to prevent people from being blown away when they do the audible beats parts.
• Use a piece of paper to cover the digital display on the generator to hide the “mystery frequency”.

• Earplugs (optional for those who are bothered by the noise)
• Extra parts
  • Function generator
  • Oscilloscope
  • Speaker(s)
  • BNC to double-banana adapters
  • Tuning forks (if available)
  • Sound level meter (if available)
  • Microwave transmitter (if available)
  • Microwave receiver (if available)