Photo-electric effect continued..
The image shown here is of a photo tube being illuminated with light from an LED. The needle on the meter is moving because a small current is being generated by the light hitting a plate in the photo-tube. There is no other source of electricity. The photons produced by the LED are knocking electrons from the atoms on the surface of the plate. These are collected by the electrode in the centre and a circuit is completed via the meter as shown in the circuit diagram below.
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