Basic Idea:

• Three experiments are performed that demonstrate diffraction and interference.

• 1 of each experiment.

	What:	How Many:	Where:
Lasers (Diffraction & Interference):
	1.0 mW He–Ne laser (Red)	3	Will be set up by faculty member You don't think I'm going to tell the world where we stash our lasers, do you?
	Scissor jack (if available)	2	Majors storeroom, shelf P2
	Mirror clip	1	non-Majors storeroom, shelf KK4
	Masked Cornell Slides	3 1 – Single slit 1 – Double slit, narrow separation 1 – Double slit, wide separation	non-Majors storeroom, shelf KK4
	Cornell Slide block	2	non-Majors storeroom, shelf KK2
	Wood platform	2 Different heights	non-Majors storeroom, shelf J2
	Poster paper/Newsprint	1 sheet	non-Majors storeroom, shelf BB5
Wavelength of Hydrogen:
	Hydrogen tube	1	non-Majors storeroom, shelf PP3
	Gas tube power supply	1	non-Majors storeroom, shelf PP2
	Masked Cornell Slide	1 Central diffraction grating d = 32,700 nm	non-Majors storeroom, shelf KK4
	Small bulbs in holders	2	Majors storeroom, shelf P2
	Meter stick clamp	2	non-Majors storeroom, shelf C3
	Small rod (50 cm)	2	non-Majors storeroom, shelf A3
	Rod base	2	non-Majors storeroom, shelf A5
	Metersticks	1 – one meter 1 – two meter	non-Majors storeroom, shelf AA1 & AA2
	Meterstick calipers	2	non-Majors storeroom, shelf AA3
	Flashlights	1 or 2	Ask Jeff
Limits of Vision:
	2x2 diffraction gratings (slides)	6	non-Majors storeroom, shelf KK4
	Incandescent display bulb (Type T - tubular, 40W)	1	non-Majors storeroom, shelf M2
	Bulb socket on-a-stick	1	Majors storeroom, shelf N4
	2m Metersticks	6	non-Majors storeroom, shelf AA1 & AA2
	Meterstick calipers	3	non-Majors storeroom, shelf AA3
	Blue Variac	1	non-Majors storeroom, shelf L6
	Right-angle clamp	1	non-Majors storeroom, shelf B3
	Flashlights	1 or 2	Ask Jeff
Work table:
	Blue Variac	1	non-Majors storeroom, shelf L6
	Hooded desk lamp with low-wattage (40W) bulb	1	non-Majors storeroom, shelf M4 & M5

Computers Needed?

• No.

• It helps to have a flashlight or two for the hydrogen wavelength and limits-of-vision experiments; makes it easier to read the meterstick.

• Make copies of "Slit Intensity Patterns" transparancy (from Jones and Childers, Contemporary College Physics, # 61, Fig 23.21. Located in Jeff's lab manual) to hand out to students.

• Map of the lab (showing where each experiment will be located):

  

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Laser setup (Photo Details):

• Top View:
• Note #1: Align lasers/Cornell slides so that the single-slit pattern appears on top, the double-slit (narrow separation) appears in the middle, and the double-slit (wide separation) appears at the bottom.
• Note #2: If scissor jacks cannot be located, the height of the Cornell Slides can be adjusted with wooden blocks or a test-tube clamp attached to a short rod.

Hydrogen tube setup (Photo Details):

• Top view:
  • Note #1: The base of the spectral tube power supply is placed up against the 2-meter stick. The 2-meter stick is positioned such that a bit of space remains so that the Cornell slide can rest on the table, and against the 2-meter stick, thus giving an accurate distance measurement.
  • Note #2: To power the small lights, connect to the DC connectors on the lab bench (set to around 6 volts).
  • Note #3: Place the metric side of the 1-meter stick facing the hydrogen tube (not the observer holding the Cornell Slide!). It is more easily read by the lab partner moving the calipers.

  

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• Front view:
  • Note #1: Place the metric side of the 1-meter stick facing the hydrogen tube (not the observer holding the Cornell Slide!). It is more easily read by the lab partner moving the calipers.
  • Note #2: Use masking tape or clamps to secure the rod bases to the table.

  

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Limits of vision setup (Photo Details):

• Top view:
  • Note #1: Place three 2-m metersticks on the floor! The meterstick placement should not begin at the wall, but directly below the bulb. Use a plumb bob to mark this position.
  • Note #2: Secure these 2-m metersticks to the floor with masking tape spaced every 0.5m. It's helpful to write the distance on the masking tape.
  • Note #3: Place two extra 2-m metersticks on the nearest lab bench. Students will use these "staffs" to measure their position.
  • Note #4: See the front view below for detail on attaching meterstick to the wall.
  • Note #5: Print three copies of this sign warning people about the meter sticks on the floor; tape to back walls above meter sticks.

  

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• Front view:
  • Note #1: Secure the meterstick to the wall as shown in detail #1 below (the left side of the meterstick simply rests on the left-hand bolt).
  • Note #2: The caliper is set at the 0.5 m mark, and the bulb filament at the 1.5 m mark (see detail #2 below); therefore, the caliper marks a distance of 1.0 m from the bulb

  

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• Limits of vision setup detail #1: attaching 2-m meterstick to the wall. Sandwich the right bolt between two calipers; the meterstick simply rests on the left bolt. This holds the meter stick in place. Align so that 1.5 m mark is directly behind the bulb filament (see detail #2 below):

  

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• Limits of vision setup detail #2: attaching bulb to wall. Use a right-angle clamp to secure bulb socket to right side bolt: