Summary

Vacuum photocell with potassium cathode, with enhanced sensitivity at the blue end of the spectrum. Intended mainly for photometry. Manufacturer: Philips, Holland.

Physical Description

Spherical bulb with tubular stem, with top cap with screw terminal. Valve type base ins missing. Potassium flashed onto inner surface of glass bulb. 'Window' left by shielding effect of mica disc.

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