# (Solved): urgent please answer all 4 to get a review, they are from the same diagram A fan system is set up in ...

urgent please answer all 4 to get a review, they are from the same diagram

A fan system is set up in a greenhouse so that the brighter the sunlight Is, the faster the fans turn. The system works by measuring the current that comes from a photocell set up on the roof of the greenhouse. A fan circult is Illustrated below: The sensor's function is to read the ammeter and manipulate the separate power supply for the fan. When the incident photons have a wavelength of $$181 \mathrm{~nm}$$, the stopping voltage for this photocell would be $$3.22 \mathrm{~V}$$. 27. a) Determine the frequency of the incident photons. (2) Your answer: 8. c) The sensor must read at least $$1.91 \mathrm{~mA}$$ of current from the Photocell circult before it will turn on the fan. Determine how many photons per second is required to hit the photocell in order for the sensor to operate? (5) Your answer: 29. d) Determine the minimum operational frequency of the photocell. (2) Your answer: 30. e) Using the principles of physics, analyze and explain how the photocell circuit. and sensor device work together to speed up and slow down the fan. Compare what happens on a bright day versus an overcast day. Why would this device be appropriate to use in a greenhouse? (2) Your answer:

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