United Scientific™ Planck's Constant Apparatus

Description

• Compact, easy-to-use apparatus
• Accurate results with less than 5% error
• Measures Planck’s constant and estimates the work function of cesium
• The Planck’s Constant Apparatus is a compact unit containing an enclosed vacuum photocell with an attachment for illuminating light sources, a high stability power supply for applying a variable stopping voltage to the cell and a nanoammeter for measuring the resulting photocurrents
• Light from five interchangeable narrow spectrum LEDs is applied to the photocell from a second integrated high stability power supply via an enclosed fiber optic connecting cable that plugs into the photocell enclosure so that the ambient illumination is excluded
• A maximum energy of the photons from each of the five LEDs in turn is measured by determining the stopping voltage for which the photocurrent becomes zero
• This occurs for the peak wavelength of each LED
• Results are evaluated by combining the wavelength and energies to allow a value for Planck’s constant to be found
• The work function of the photocell cathode material can also be estimated
• This can be performed graphically, analytically, or using the included Microsoft Excel™ spreadsheet
• Planck's Constant Apparatus Specifications: Photocathode Material: Cesium (Cs) Voltmeter Display: 3.5 Digit, LCD, precision 0.5% (typical)
• Ammeter Display: 3.5 Digit, LCD, precision 1% (typical)
• Dimensions: 28 x 12 x 16 cm Weight: Approx
• 1 kg