Question

For what purpose can devices like the phototransistors and the photoelectric cell be used?

Answer 1

1. Devices like phototransistors and photoelectric cells are used as a detector of visible light.
2. When light rays strike phototransistors and photoelectric cells they convert light energy into electric energy.

Hence, devices like the phototransistors and the photoelectric cell are used as a detector of visible light.