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by Procheta Mallik

Introduction

This simple representation of a tidal turbine was created by a 9-yr-old girl in a small village in Maharashtra. Her name is Durga, and so this toy has the monicker "Durga Jetty". By winding a copper coil and attaching a magnet to the turbine, one can also create a tidal generator that lights up an LED. Durga's story is inspirational. She used to go to school in the morning and in the afternoons used to help her mum, who worked as a domestic help, with chores. On the riverbank, during one of these boring afternoons, she gathered trash thrown around and created this wonderful model. This was recognised by the government of Maharashtra, who gave her a scholarship to study through school and college. Durga today is a professional engineer and her creation has brought joy and learning to countless children in India, hopefully inspiring a new generation of innovators from across the country.

Video Overview

    • Exercise caution when using the scissor and cutter.

    • There's no need to open the safety pins; beware of them if they open out.

    • Mind the pointy ends of the binding wire.

    • Beware of the cut end of the bottle as it might be sharp.

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  1. Take a cardboard of length slightly more than 12cm ( say 12.7cm) and breadth 1.5cm.
    • Take a cardboard of length slightly more than 12cm ( say 12.7cm) and breadth 1.5cm.

    • Fold them like an accordion with each fold about 2cm in length.

    • Open the folds. You get a zigzag strip of cardboard.

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    • Apply glue on one of the sides of the strip,preferably on the rougher side.

    • Compress the glued sides together.

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    • Apply glue at the middle of your 8 cm thick binding wire.

    • Insert it through the centre of the turbine as shown.

    • The turbine has to stick firmly with the binding wire. It shouldn't move about its position.

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    • Make a hole slightly off-centre in the bottle cap using a scissor.

    • Take a long strip (about 12cm) of tape and place a safety pin at 2cm from one end of the tape.

    • The safety pin has to be placed with it's head on the sticky side of the tape.

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    • Fix the safety-pin on your bottle cap with one end of the tape left open.

    • Place another safety pin diametrically opposite the first one and seal it with the open end of the tape.

    • The safety pins have to positioned at 3 o'clock and 9 o'clock with the cap hole at 12 o'clock (or 6 o'clock). Only then will the air hit the turbine most directly.

    • Place your turbine between the two safety pins by inserting the binding wire through the holes of the two pins.

    • The turbine with its axle should be able to rotate freely between the pins.

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    • Take a plastic bottle and cut its base using a cutter/scissor.

    • Close the bottle with the turbine cap.

    • Fill a vessel with water as shown.

    • Note that the vessel opening should be bigger than the diameter of the bottle with turbine so that it may be inserted easily.

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    • Place your turbine bottle in the vessel filled with water and move it up and down.

    • The bobbing motion should produce a jet of air coming out of the bottle cap hole, which in turn will spin the turbine.

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    • The length of the turbine bottle is small.

    • The turbine blades are not directly above the hole, or if the turbine keeps sliding around.

    • The safety pins aren't placed opposite to each other or are not at the same height.

    • The movement of turbine bottle in water is not quick enough.

    • The pins are too short, or the turbine blades too long. This causes the blade to hit the bottle cap and prevent it from spinning freely.

    • The jet of air hitting the centre of the turbine; this too would produce no rotation. This can happen if the bottle cap hole is right at the centre.

    • The pins are too long or blades too short. This makes the distance between the blades and the bottle caps, hence reducing the effect of the jet of air.

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    • Does varying the up and down speed of hand affect the speed of the turbine?

    • How does the blade area influence the speed of rotation ?

    • In which direction does the turbine spin? Can you change the direction of the spin?

    • What will happen if a hole of the same size is made opposite to the already existing hole?

    • Does changing the size of the hole on the bottle cap affect the speed of the turbine? If yes, does it increase or decrease?

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    • To measure the time you can use a stopwatch which is available on the phone or most digital watches these days.

    • Hold the bottom of the bottle just at the brim of the water. Make sure your stopwatch is at 0.

    • Now immerse the bottle all the way to the brim while simultaneously starting the stopwatch.

    • Immerse the bottle only once.

    • Wait for your turbine to stop spinning. Once it stops, stop your stopwatch. Note this reading and repeat it 5 times.

    • Take average of the five readings. Based on the values you can find out which variation of turbine spins for the longest.

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    • Take a cardboard of length of slightly more than 20 cm (say 20.8 cm).

    • Fold them like an accordion with each fold of almost 2cm length.

    • Open the folds . You get a zig-zag like pattern.

    • Now follow step 3 and 4 again.

    • Play with the new 5 bladed turbine.

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    • Cut a circular piece from the foam piece.

    • Apply glue at the centre of the rod and pierce the metal rod through the centre of the circular foam.

    • Make slits at the poisition of 12o'clock , 4o'clock and 8o'clock.

    • Take an ice cream stick and cut it into 3 equal parts.

    • Apply glue at the slits made and insert the ice cream stick pieces into the slits.

    • Try out your new wooden turbine.

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    • Take a similar bottle as used in step 7.

    • Make a cut halfway instead of cutting at the lower end.

    • Replace the old bottle with this newly cut bottle.

    • Play!

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Finish Line

Vishal Bhatt

Member since: 04/26/2017

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50 Guides authored

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