Product Overview
Before the invention of photodiodes and phototransistors, the only way to measure light was by using a photo cell or photo-tube. These devices are sealed glass tubes with connection pins at one end to allow for insertion into a socket. Sometimes they were filled with an inert gas, and sometimes they were evacuated. Inside the glass tube was typically a curved metallic cathode and a straight pin anode standing up in front of it.
The cathode was coated with a special caesium and silver alloy that made it easy for photons of light to knock electrons from its surface. The flow of electrons from the cathode to the anode pin increased as light intensity increased. This flow is known as the photo current, and it was used to measure the amount of light falling on the cathode. These same devices were also used as photo switches to trigger alarms when a beam of light was broken.
For a complete self-contained photoelectric experiment unit for demonstrating the phenomena and for calculating Planck’s constant, see SKU 28-543200.
Specifications:
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Physical size: 115 × 82 × 70 mm (4.5 × 3.2 × 2.8 in)
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Weight: 0.1 kg (0.22 lb)
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90CG gas-filled tube operates at 90 V DC applied to the anode/cathode circuit
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Dark current: <1 µA
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Bright current: >200 µA
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Spectral response is toward the red end of the spectrum, well-suited to incandescent lighting
Designed and manufactured in Australia.
