Basic Idea:

• Measure the stopping potential and binding energy for ejected electrons.

• 7

	What:	How Many:	Where:
Note: One Mercury source is used for two setups per bench!
	Pasco Mercury Light Source See photo below	1	non-Majors storeroom, shelf DD3
The following components are for each setup; there are up to two setups per lab bench!
	Light Aperture Assembly See photo below	1	non-Majors storeroom, shelf DD4
	Lens/grating assembly (blazed) See photo below	1	non-Majors storeroom, shelf DD4
	Photoelectric head (Units A, B, D, E, F, G, H, I) See photo below	1	non-Majors storeroom, shelf DD4
	Support base See photo below	1	non-Majors storeroom, shelf DD4
	Coupling bar See photo below	1	non-Majors storeroom, shelf DD4
	Filters: green, yellow and variable transmission See photo below	1 each	non-Majors storeroom, shelf DD4
	Light Block (optional - only needed when one side of Hg source is not used)	1	non-Majors storeroom, shelf DD4
	Digital Multimeter	1	Majors storeroom, locked in steel cabinet
	Wires	Three 36" (1 red, 1 black, 1 purple or gray - if possible) Two 24" (1 red, 1 black)	Bewkes 231 (Phys 152 Lab), Majors storeroom
	Flashlight	2	non-Majors storeroom, shelf CC3
The following components are installed on instructor's bench; Ask Jeff if we're using One Dual-power supply (preferred) or Two single-power supplies!
	Either: Dual power supply (preferred)	1	Majors storeroom, shelf C2
	Or: 40v regulated power supply	2	Majors storeroom, shelf C2
	Digital Multimeter	1	Majors storeroom, locked in steel cabinet
	Wires	Five 12" (2 red, 3 black) Two 24" (1 red, 1 black)	Bewkes 231 (Phys 152 Lab)
	Window Blocks	1 each window	non-Majors storeroom, shelf S3

Notes:

• Lab setup (photo details):
  • Place apparatus at an angle for easier access
  • Use photo heads in positions as shown
  • The grating must be installed with the label on the same side as the photo head wire connections (the thumb screw will be at the bottom); see these photos for orientation!

  

   

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• Mercury light source:

  
  Image courtesy PASCO Scientific.

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• Photoelectric head and filters: yellow, variable transmission and green

  
  Image scanned from PASCO Scientific catalog.

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• Light aperture assembly, support base, lens/grating assembly (blazed), coupling bar:

  
  Image scanned from PASCO Scientific Instruction Manual.

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• The whole setup (connect two per mercury source):
  • Note: Attach the lens/grating assembly so that its label is on the same side as the electrical connections in the photoelectric head! This will put the brighter side of the spectrum on the "near" side of the student.

  
  Image scanned from PASCO Scientific Instruction Manual.

• Power supply connection:
  • Note: Main DC power panel must be disconnected before the power supplies are used! Jeff will take care of this.
• Use one dual-power supply (set to independent), or two single-power supplies connected in series; the left supply is set to -9.0 volts and the right to +9.0 volts.
  • During Spring 2023, I used a different dual-power supply than the one in the drawing below, one with a ground connector for each side. See the photos details page for its connection (requires one additional 12" black wire)

Connection of Dual Power Supply	Connection of Two Single-Power Supplies

• Photoelectric head power connection:

Note the additional ground wire connected to the green connector on the power panel. Only the newer photo heads require this connection, yet all will work properly when connected thusly.