Author Archives: Arun Surya

Making Homopolar motor with 7th graders

Janani and Vishal made a homopolar motor. Janani got excited when she saw this experiment online and she wanted to build one on her own.

Making:

Materials needed: 1*AA battery, 3*neodymium magnet, Coper wire of length30cm.

Step 1: Place the three magnets at the negative terminal of the battery.

Step 2: Bend the coper wire as shown in the figure. Make sure it is not insulated, if so please scratch the wire till you get rid of the enamel.

Step3: Put all of them together. Place the coper bend wire on top of the positive terminal of the battery and other end touching the negative terminal of the battery.

Take a look at the video:

  • The current in this homopolar motor flows in the presence of a magnetic field. When a current flows in a magnetic field, it will experience something known as the Lorentz force. The Lorentz force is what causes the wire to spin around the battery.[1]
  • The wire connects to the battery at three points. One point of the wire is on the positive terminal, and the two ends of the wire are near the magnet, on the negative terminal. The current flows out of the positive terminal and down both sides of the wire. The magnetic field pushes the current outwards, causing the wires to rotate.[2]

sources:

 

 

Half wave and Full wave rectifier

I made a model of Half wave and Full wave rectifier using LT spice.

Half wave rectifier:

A half wave rectifier is a device which makes use of properties of a pn junction diode. A PN junction diode only allows the current when it is forward biased. When it comes to real life application we need DC voltage. This circuit converts AC to DC voltage.

Full wave rectifier:

A full wave rectifier uses two PN junction diode which is more efficient and burns less power. It uses both the cycles of the AC wave and gives a smooth curve.

Spinner: MIT app inventor

A child from 7th grade made a spinner using MIT app inventor. He took 3 weeks to complete the project.

MIT app Inventor: It is an application where you can make mobile app. It is similar to scratch where you can stick blocks.

The child shares his experience in the video and how he made it.

 

Soldering and Tinkering

Children of Isaimbalam were very much interested in Soldering and making simple circuits. We got many Vega kits were the circuits are already printed in a PCB. Children study the datasheet of a particular circuit and solder. Children from 6th and 7th soldered few kits. They were very happy when some of them worked.

Since they are young and new they made mistakes by flipping few components here and then but they tinkered with my help.

Circuits like Disco light, Light sensor and water level indicator worked.

Bala was so happy when we were testing the water level indicator and the light one by one lighted up. Auyush also connected a buzzer to indicate low light.

Ayush and Swetha testing low light sensor

Ayush and Swetha testing low light sensor along with me

Sabari and Vasanth with Disco light

Sabari soldering the kit

Water level indicator by Bala

Measuring Kitchen tank Volume in Isaiamabalam School

Children wanted to make a recycling water system to water the magic garden. We thought of using the waste water from the kitchen to water the plant since so much of water is daily used to wash the vessels, clean vegetables etc. To know the amount of water used daily for the kitchen we need to know the volume of the tank. Kavitha told that the volume of the kitchen tank was 2000 L.

To make sure of what we know already we measured the height and circumference of the cylindrical tank in order find the volume of the tank.

Measure height:

  • To measure the height of the tank we used a bamboo stick.
  • Children marked the height of the tank on the bamboo stick.

Measure Circumference to determine radius:

  • We used thread to know the circumference.
    Children took the thread around the circular shaped ring and marked on the thread.
  • The challenging part was we was not able to find the measuring tape. Then we came up with an idea to use the metre scale chiildren already used.

We found that the height of the tank was approx 3 m and Circumference to be around 3.14 m.

Through this we found out that the radius was half a meter.

Finally we found out that the tank volume was approximately 2355 L.

This might be an error with calculating the circumference of the circle because we found the distance outside the ring and not inside.

Measuring the circumference of the circle with the one meter scale and the left over part was measured using a 30 cm scale

From Left: Ajay, Gurumoorthy, Pravin, Kalai

Children measuring the length of the bamboo stick to measure the height of the tank. They used the same thread to measure the length. They marked 3 m on the thread in order to do this

Children calculating the volume of the tank

 

Exploring Botanical garden

3rd graders and 5th graders went for a walk around the botanical garden in Auroville. Sathiyamoorthy was guiding us.

Prathap, Bala and myself were along with the children. We started with a circle and Sathiyamoorthy gave a brief introduction about what the children should do and the type of plants they were expected to see around the Botanical garden. He was basically telling about 4 types of plants.

  1. Epiphytes (Plants that has the roots outside the soil.)
  2. Xerophytes (Plants that grow in dry areas. (Eg., Cactus))
  3. Semiphytes (Plants that grow in land.)
  4. Parasites (Plants that grow on other plants and trees.)
  5. Hydrophytes (Plants that grow in fresh water.)
  6. Halophytes (Plants that grow in salt water. Note: These types of plants are not there in Auroville Botanical garden)

Then the children went around and Sathiyamoorthy explained about the plants. He talked about the survival techniques, leaf structure and mainly names of the trees and plants.

Children played a maze game. A garden with a maze structure was built there. Children enjoyed getting lost and finding the paths. Children also reflected at the end of the session.

Starting the session with Concentration

Introduction by Sathiyamoorthy

Epiphytes

Epiphyte garden

Explaining about the root

Maze garden..

The Xerophytes garden

Laasya (2nd grader) writing the plants names.

Explaining various Xerophyte plants

Reflections after the walk

Lemon grass tea for the children

Children enjoying the tea

 

Magic garden

First the class started with how many plants 5th graders wanted to plant in the garden. Then we decided to plant one plant for each foot. The problem started there. Children doesn’t know how much a foot is. Then the conversation went on and the children said that a foot is our foot. Exactly the foot is our foot. A foot is approximately the size of an adult foot. Then the children converted the meter dimensions of the garden they earlier measured into foot.

We went to Botanical garden after that to buy plants. Children were excited and we chose some plants and bought them. Then we came and planted them in the garden.

Each child took different responsibility and planted all the plants. Anitha gave few plants she had.Children also wrote the names of some plant they saw in the Botanical garden.

Children looking at different plants

Writing the names of plants

Looking around and finding more plants

Planting activity were children took different responsibility

Planting

 

Garden – Filling up with sand

Saturday school already started with disappointment when the hot air balloon again failed to raise up. Then we thought of finishing with what we started. The garden which we built has to be filled with soil to plant plants. It was somewhat time consuming and exhausting to get red soil outside school. Then we looked around the school and found interesting solution.

There were burnt ashes left and decomposed compost from the dry leaves of bamboo trees. We decided to mix Ashes, Sand and Dry leaf compost to fill the garden. The activity started and the children mixed them and almost filled the garden.

Getting Wheel barrow and other tools

Collecting dried leaves compost

Collecting sand

Collecting sand

Mixing Ash, Dried leaves compost and sand

 

Hot Air Balloon

We made a big hot air balloon. We already completed making the balloon along with the 5th graders. Today for the Saturday’s class we decided to make it fly.

We got some old cloth and some kerosene to get hot air from the fire. We lighted it up and held the balloon on top to get hot air going in. The balloon was a big spherical structure. We waited for a long time and couldn’t get the balloon filled with hot air.

Then we discussed with the children on why the balloon did not go up. Their assumptions were

  1. The Balloon had holes in the structure.
  2. Hot air did not go inside.
  3. The balloon was too heavy. (We weighed the weight of the balloon and it was 206 g)
  4. The balloon was not properly made.

Then we decided to make a small balloon and check if it was flying. This time we made a cuboid balloon structure whose height was around 50 cm high. Again with a lot of excitement we filled the balloon with hot air. We waited and waited but it could not go up. We still don’t know the reason why the balloon did not rise up???

All children excitingly seeing the hot air balloon

Lighting up fire

Holding fire and balloon on to top to fill hot air inside the balloon

We are waiting to see one go up.