Site Navigation

Your Account

Choose Language

1.1

Minor Versionm

by Kailash NR

Introduction

Make a conductive paint and use it to create your own resistor.

    • Scissors have functional sharp edges. Contact may result in injury.

    • Always keep blades away from fingers and body. Handle with care.

  1. To make the battery holder please visit this link DIY Battery Holder - Foam and Spring.
  2. The longer leg is the positive terminal. Connect the wire from the negative terminal of the battery to negative terminal of the LED. Attach another wire to the positive end of the LED. Keep the other end free.
    • The longer leg is the positive terminal.

    • Connect the wire from the negative terminal of the battery to negative terminal of the LED.

    • Attach another wire to the positive end of the LED. Keep the other end free.

    • Remove insulation from both the ends of the wires before you connect to LED or battery.

  3. Keep the wire from the positive end of the battery free.
    • Keep the wire from the positive end of the battery free.

    • We are going to use the free ends to check the conductivity of different materials.

    • You can also keep a longer wire ready to attach it on the positive end. This is only useful for checking bigger objects.

  4. The wires are now your test leads. Use these test leads to test various materials for their conductivity. Never bring the test leads in contact with each other; keep them at least 2-3cm apart on every object that you test. If the LED does not glow, it is an example of a negative result, in this case the material is an insulator.
    • The wires are now your test leads.

    • Use these test leads to test various materials for their conductivity. Never bring the test leads in contact with each other; keep them at least 2-3cm apart on every object that you test.

    • If the LED does not glow, it is an example of a negative result, in this case the material is an insulator.

    • If the LED glows, it is an example of a positive result, in this case the material is a conductor.

    • The connections between the battery and safety pin might be loose, in that case hold the two terminals with your thumb and index finger for a better connection.

    • Make sure all the connections are clean and stable, otherwise the current will not flow.

    • To ensure proper connection, wind the wire several times over the material.

  5. Does the brightness of the LED vary among different conductors?
    • Does the brightness of the LED vary among different conductors?

    • Conductivity is directly proportional to brightness of the LED. (True/ False)

    • Are all metals conductors, and all non-metallic substances insulators? (Yes/No)

    • Can an LED be connected in any direction and still work? Can you think of any other use for this property of the LED?

    • Why is it important to connect the batteries as we did here? Are there other ways of connecting multiple batteries?

    • Use the observation table shown alongside to classify the materials into good and bad conductors and insulators.

    • Good conductor - LED glows brightly. Bad conductor - LED glows dimly. Insulators - LED does not glow.

  6. Try to check some bigger materials like iron rod, bicycle wheel rim, cricket bat etc. Try to check the conductivity of liquids like milk, curd, lemon juice or any other fruit juice. If you want to check the conductivity of even more materials, please click on this link Electrical Conductivity (Variations).
    • Try to check some bigger materials like iron rod, bicycle wheel rim, cricket bat etc.

    • Try to check the conductivity of liquids like milk, curd, lemon juice or any other fruit juice.

    • If you want to check the conductivity of even more materials, please click on this link Electrical Conductivity (Variations).

    • Be mindful of the battery terminals, they can heat up or momentarily spark if an electrical short occurs.

  7. Start with about half gram of graphite power in a  small saleable container. To this add 2 drops of  white (PVA) glue. Use the dropper to measure out 1 ml of water and add it to the mixture.
    • Start with about half gram of graphite power in a small saleable container.

    • To this add 2 drops of white (PVA) glue.

    • Use the dropper to measure out 1 ml of water and add it to the mixture.

  8. Use the dropper to stir the mixture till it's of an even consistency and is free of lumps. The paint is now ready to use.  For long term storage, dilute it with more water  and store in an air tight container.
    • Use the dropper to stir the mixture till it's of an even consistency and is free of lumps.

    • The paint is now ready to use. For long term storage, dilute it with more water and store in an air tight container.

  9. You'll need an ice-cream stick and  two pieces of copper tape that are 2.5 cm each. Peel the paper cover off the tape to expose the stick side. Stick the tape on one end of the ice-cream stick .
    • You'll need an ice-cream stick and two pieces of copper tape that are 2.5 cm each.

    • Peel the paper cover off the tape to expose the stick side.

    • Stick the tape on one end of the ice-cream stick .

  10. Wrap the tape around and stick it back to itself. Repeat the same steps to tape the other end of the stick as well.
    • Wrap the tape around and stick it back to itself.

    • Repeat the same steps to tape the other end of the stick as well.

  11. Measure out 0.5 ml of  the paint with the dropper. Carefully draw a line from one copper strip to the other, dispensing most of the paint as you do so. Make sure both ends of the paint line touch the copper strips.
    • Measure out 0.5 ml of the paint with the dropper.

    • Carefully draw a line from one copper strip to the other, dispensing most of the paint as you do so.

    • Make sure both ends of the paint line touch the copper strips.

  12. Now smear out the paint on the  surface of the stick till there is a uniform  and uninterrupted trail of paint  between the copper strips. Cover about half the width of  the tape  pieces with paint as well. This will ensure good electrical contact between the copper terminals and the graphite. Now leave the stick undisturbed to dry, this can take upto an hour, depending on the ambient temperature . When its done the graphite layer will be more grey than black  in colour and have a slight metallic glint to it.
    • Now smear out the paint on the surface of the stick till there is a uniform and uninterrupted trail of paint between the copper strips.

    • Cover about half the width of the tape pieces with paint as well. This will ensure good electrical contact between the copper terminals and the graphite.

    • Now leave the stick undisturbed to dry, this can take upto an hour, depending on the ambient temperature . When its done the graphite layer will be more grey than black in colour and have a slight metallic glint to it.

  13. Set up the  conductivity probe as shown in this guide. This is a simple circuit consisting of an LED that will help test  the conductivity of the strip. Close the circuit with no load connected, just to get a feel for the maximum brightness of the LED. If you are using a Red LED with brand new (unused) batteries, it is recommended that you do not perform this check as the LED may burn out.
    • Set up the conductivity probe as shown in this guide. This is a simple circuit consisting of an LED that will help test the conductivity of the strip.

    • Close the circuit with no load connected, just to get a feel for the maximum brightness of the LED.

    • If you are using a Red LED with brand new (unused) batteries, it is recommended that you do not perform this check as the LED may burn out.

    • Connect the two leads of the tester to the copper strips on either end of the stick. The LED should be illuminated, if a little dimly.

  14. LED connected directly. LED connected through the graphite stick.
    • LED connected directly.

    • LED connected through the graphite stick.

    • The connections between the battery and safety pin might be loose,in that case hold the two terminals with your thumb and index finger for a better connection.

    • Make sure all the connections are clean and stable, otherwise the current will not flow.

    • Ensure proper connection to the copper contacts.

Finish Line

Kailash NR

Member since: 05/02/2017

4,021 Reputation

88 Guides authored

0 Comments