Precise Determinations of Photoelectric Effect

• Study electron photoemission from a metal surface
• Obtain the characteristic curves of a vacuum photocell
• Explore the effect of illumination intensity using the inverse square law

Examine the photocurrent produced by an illuminated cathode with this convenient apparatus. A current-controlled filament lamp in a light tight box illuminates a photocell with a mixed-alkali cathode. The control unit supplies a controlled bias voltage and delivers the photocurrent to a sensitive current amplifier so that the characteristic curve ofthe photocell as a function ofthe bias voltage can be precisely measured. The filament lamp is mounted on a slide with a scale, so that the relative illumination level can be adjusted by changing the distance of the lamp from the photocell. This enables a characteristic curve of photocurrent as a function of illumination to be constructed. The control unit carries multi-tum potentiometers for adjusting the lamp current and the bias voltage, and pushbuttons for selecting the photocurrent measuring range. The lamp current, bias voltage, and photocurrent are displayed on three built-in digital readouts. A user manual is included, in addition to a test box and set of connecting cables. 110 VAC, 128 W. Size: Test Box: 15cm H x 13cm W x 62cm L; weight 3.6 kg. Control Unit: 10cm H x 35cm W x 28cm D; weight 4.4 kg.