Here is a really simple experiment in witch you will make a Kind of potentiometer (Variable Resistor) out of a sheet of paper and a graphite pencil (Lead Pencil)... Impossible you think? Check it out!
So first , What is a Potentiometer?
Its not very complicated, to make it short, it's a kind of resistors ( Limit the current flow) but its adjustable, so you can raise or lower the limit of the current flow.
I recently seen a video of MAKE Magazine (MAKE : Present The Resistor) on Youtube in witch they were doing something similar to this and thats where I got the idea to make an Instructables about how to make this simple Variable Resistor.So I have no credit for the idea, I just did an Instructables, to share it with you!
The Idea is to draw a band (with a Graphite pencil) on a sheet of paper ,the band of graphite will act as the Variable Resistor (Potentiometer) because the graphite conduct electricity but poorly.
Add a Teacher Note to share how you incorporated it into your lesson.
Step 1: Material
- Sheet of paper
- Pencil [You need a very soft one like 2B+ (Less may not work properly)]
- an LED
- Alligator clips (2)
- Source of power (9v battery is good)
Step 2: Draw the Variable Resistor
On the sheet of paper , you will need to draw a band about a centimetre wide and 5cm long and full it up with Graphite pencil. ( You can also try with longer band! ).
Step 3: Testing With the Multi-Meter
Step 4: Testing With LED - Assembly
You can also test the Variable Resistor with an LED. Here is how to do it: First connect your 2 alligator clips to the 9V (one on each pole), then connect the Negative clip to the negative lead of the LED, and finally, bend the positive lead of the LED(Anode, the longest) so its easy to move on the paper and it gives good contact. ( If you don't have any alligator clips, you can replace them by normal wire, simply twist around the components to make the contact, or solder ) *Tips : If you don't know witch lead of the LED is - or + , test out with a button cell !
Step 5: Testing With LED - the Test
Step 6: Experiments!
Try wider or longer lead band or try other patterns and see what happen..! Try with other conductors like metals or anything else you know! Try with other kind of pencil (2H, 2B...) Try colouring lighter or darker for different result! Experiment, Experiment, Experiment ! and have some fun!!
Hope you enjoy !