Electric Field detector

Published on 18 Apr 2022. Written by Athulya Menon

Most people who work with basic electronics would tell you that the worst part about it is getting small electric shocks! So what do we do to prevent this? But working with electrical components isn't the only time you get shocks. You can also get small shocks when you walk on a dry carpet, or even when you touch a doorknob sometimes.

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In this science project, we will be looking at ways to detect the presence of static electricity.

Project Description

Most objects we encounter are electrically neutral, that is due to the fact, they have an equal number of positive and negative charges within them. But, when two different materials are rubbed against each other, charges get passed from one object to another, and this might lead to more positive charges accumulating on one surface, or more negative charges accumulating. Such an accumulation of charge will lead to the development of an overall positive or negative charge on the surface or object. The donation of electrons on contact is what leads to such an accumulation.

Such a charge accumulation leads to the generation of static electricity, which leads to small shocks. This project aims to build a sensor that can sense electric fields before you touch it so that you can prevent getting zapped! It is also a great way for school children to get introduced to the world of electronics.

What is Static Electricity?

Shocks from carpets and other such dry things are due to the presence of static electricity. So what is static electricity?

Static electricity results in the accumulation of charge on a surface, or object and this may be caused due to either contact or separation of charges. The sparks which form as a result of this charge accumulation leads to more severe repercussions such as the shorting of components on devices, which leads to the failure of machines.

Electrons are elementary atomic particles that have a negative charge. When an electron gets passed on from one surface to another, the object that receives the electron gets an extra negative charge. Therefore, whenever electrons are exchanged, charge neutrality is disturbed, leading to the formation of charge. Likewise, giving up an electron makes the object more positive, again, leading to the accumulation of positive charge.

Triboelectric Series

The triboelectric series lists materials according to their ability to hold or let go of electrons. This, in turn, decides the nature of charge accumulated on the object, and in later stages, decides on easily an object will produce static electricity. The ones higher on this list are more liable to give up electrons, and hence turn positive, when rubbed with another material on the list.

• Hands
• Glass
• Hair
• Nylon
• Wool
• Silk
• Paper
• Cotton
• Steel
• Wood
• Nickel, copper
• Polyester
• Silicon
• Teflon

Project Implementation

1. A FET has three leads, being a source, gate, and drain. When there is no electric field, it allows current to flow.
2. This device when subject to a field, does not allow much current to pass through, leading to the LED is turned off.
3. Varying gate voltage can be used to modulate the amount of current through the circuit.
4. As the gate voltage becomes more negative, it blocks the current path near the vicinity of the gate, thereby increasing resistance and reducing current.
5. Assemble the detector as shown in the circuit diagram on the breadboard.
6. Be careful while assembling so as to not burn out the LED or transistor. Make sure you insert the right pin in the right slot.
7.  Always count the number of rows in the breadboard to assemble the circuit correctly.
8. Avoid touching the transistor leads by hand to prevent static discharge which can lead to malfunctioning of the transistor.

Concepts Used

1. Basic Electronics
2. Circuit making and Design
3. Experience with a breadboard/soldering
4. Electric properties of materials
5. Fundamentals of static electricity
6. Fundamentals of semiconductors

Components Required

• 9 Volt Battery
• LED
• Field-effect Transistor
• Jumper Wires
• Breadboard
• Battery connector
• Resistors

Kit required to develop Electric Field detector:

• Battery
• LED
• Breadboard

Technologies you will learn by working on Electric Field detector:

• Electric
• Semiconductor

Any Questions?