We all come across electric effects and its phenomena throughout our daily lives. From lightening in clouds to static in dry clothes are all related to electricity. Electric energy drives the living and economy of modern societies. If we look at possible sources of electricity around us, there are plenty of them but in the majority of situations, electricity is generated on the very principle of electromagnetic induction.
Electricity can be generated in many ways like by means of electrochemistry ( batteries ), photoelectric effect ( solar cells ), piezoelectric effect ( piezo-transducers ), thermoelectric effect ( Peltier chips ), electromagnetic induction, etc.
In this instructable, we will do a very simple and interactive demonstration of how electricity is produced. Here we will demonstrate two physics principles: Electromagnetic induction and Piezoelectric effect.
This instructable is best-suited for grade 4 to 10 students and requires a duration of 30 mins.
Add a Teacher Note to share how you incorporated it into your lesson.
Step 1: List of Materials
- Simple DC Motor ( Geared preferred if available )
- Piezoelectric Plate
- Connecting wires
- Soldering Iron+Wire
Step 2: Soldering Connecting Wires
Solder connecting wires to motor pins and piezo plate. while soldering piezo plate make sure to solder white silvery disk for one wire and the golden portion for other.
Connect LEDs to the motor and piezoelectric plate. Congrats! your setup is ready for demonstration and play.
Step 3: Electricity From Motor
Turn the motor shaft firmly ( you can use a wheel for sake of ease in turning motor shaft as I did ). LED will glow on turning the motor. Faster the motor shaft rotates, brighter the LED glows.
Note: Since LED is a polar device ( having positive and negative leads) check for LED glow by rotating the motor shaft in both directions and look for the right arrangement of LED leads connection and motor turning direction. In simple words, you should rotate in another direction if it does not glow for the one.
This is the case of electricity generation by electromagnetic induction. You can teach your students this elegant and amazing phenomenon through this simple demo. Actually, Electric motor and generator are conceptually one and the same thing but design varies obviously depending upon the application.
Electric Generator : Mechanical Energy to Electric Energy
Electric Motor : Electric Energy to Mechanical Energy
Step 4: Electricity From Piezo-plate
When stress or strain is applied to a piezoelectric material a nominal amount of potential/voltage is induced across its faces. We can harness this kind of electricity by designing proper plate geometries and installing them in multiple combinations across stress creating and vibrating environments.
For this demo hold the piezoelectric+LED setup and gently tap on it, try to bend it, press it. LED will glow due to stress and strain created in the plate. Higher the change in stress or strain, brighter the LED glows.
Step 5: Motivation for Students and Teachers
These two demos are just a glimpse of those cool and amazing projects you can make with these concepts.
- You can install a piezo plate in sole-pad of shoes and make battery charging or power shoes. when we walk our feet continuously produce high changes in stress and strain of shoe sole-pad.
- SImple DC motor can be used as a dynamo/generator in various science projects say bike powered USB charger.
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