How do you make a simple circuit using a potentiometer, photo cell & 9Volt battery?

Question

How do we make a simple circuit using these items???
My daughter is doing a science project. She has painted a shoe box black, and has a photo cell inside the box with the wire ends ot the photo cell extending outside the box. She has a divider running half way down the middle of the box. At the end she has a stand to place a ball on. She has painted several different colored balls, and will place them on the stand, and wants to see the different readings using a volt meter using a potentiometer. She has a hole in one end where she will use a flash light to see how it relects/volt meter reads off the colored balls.
We are having lots of problems trying to help her hook up this simple circuit. I thanks you in advance for your input!

Answer 1

You will need a Digital Volt Meter (DVM) to measure either the resistance of the cds Photocell or an output voltage from a voltage divider.

The cds Photo cell changes its resistance with the amount of light hitting it. (it is also color sensitive so different colors of light at the same intensity will give you different results)

Photo cells come in different resistance values ranging from 1K to 1meg ohms. If you are not handy with basic electronics meaning: Ohms law, Voltage divider, and series circuit. Than using a DVM to directly measure the resistance will be far easier than hooking up the Cds Photo cell in a series circuit with a potentiometer as a voltage divider and measuring the output voltage. (see link)

If you hook up a voltage divider do the following.

Connect wire from the negative pole of the battery to one of the leads on the Photocell. Connect another wire from the remaining lead of the photo cell to the middle connection on the potentiometer. Finally connect a third wire from one of the remaining potentiometer leads and connect it to the battery positive. This creates a voltage divider which is two resistances in series. You measure the voltage across the cds Photocell using a DVM. This voltage will change when either the amount of light is changed or it the potentiometer is adjusted.

One important hint. The value of the powentiometer should be approximately the max value of teh photocell.

A 4K to 10K photo cell should use a 10K pot. This will give the maximum sensitivity and adjustment range of your voltage divider.

Answer 2

Simple Potentiometer Circuit

Answer 3

You have nothing in the list to act as an indicator

you need a voltmeter or multimeter

you wire the photocell in series with the potentiometer
and wire the battery to the ends

adjust the potentiometer to give 4.5 volts on the voltmeter connected to the mid point of the photocell and potentiometer

The low side of the voltmeter goes to battery negative


(do not have the potentiometer set to 0 Ohms)

these have 3 connections
one end of the resistance
the other end of the resistance
and a wiper that traverses from one end to the other

To make a variable resistor (that you need for your circuit to work) you must connect the wiper to one end of the resistance

perhaps labelled 1 2 3 (if 3 is the wiper join it to 1 OR 2)

then as you wind the potentiometer it goes from maximum resistance to zero

Answer 4

Connect the voltmeter across the potentiometer(pot). Then connect this combination in series with the photocell and t.he battery.As the light sensed by the photocell increases, the voltage across the pot will increase.