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Winnowing is a type of separation method through which husk is separated from grains. This technique of separation has been in use since ancient times. It simply involves throwing the mixture we want to clean, into air so that the lighter chaff particles are blown away. Winnowing is a crucial process in the cultivation of paddy. The traditional way of winnowing is making the dried grains fall from a height using shovels and a sieve. The word winnow is derived from the English word ‘windwian’ which represents the separation of mixture with the help of air.
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Key Terms: Seperation, Mixture, Wind, Paddy, Particles, Climate-friendly
What is Winnowing?
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Winnowing can be defined as the method or technique through which lighter particles get separated from heavier particles with the help of wind. This type of process is used only for the mixtures which have both the particles in solid form and one particle is lighter than the other one so that it can easily be blown away with wind. The grains which are heavy fall vertically while the weightless chaff and straw get blown away by the wind. And so, winnowing is effective only when there is a wind. That is why farmers often have to wait for hours for the wind to blow before they could start the process of winnowing.
Winnowing doesn't need any type of heavy machines but some machines have been designed for it. The first machine was designed in the year 1737 and is known by the name wind winnowing machine. The modern day machine is a combination of threshing and winnowing.
Process of Winnowing
Principal of Winnowing
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The principal of winnowing is based on the difference in mass of the components of a mixture. If the mixture contains two components, one is lighter in weight and other one heavier, then they can be separated by winnowing. The mixture is taken at a height and is allowed to fall down while the wind is blowing so as the lighter components will blow off by the wind, and the heavier ones will fall down.
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Advantages and Disadvantages of Winnowing
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Some of the advantages of winnowing technique are given below:
- Winnowing is a crucial process in the cleaning of grains.
- It doesn’t involve any machine so it is a climate-friendly technique.
- It is also a cheaper technique.
- It is a pollution free method and has less maintenance.
Some of the disadvantages of winnowing technique are given below:
- Through this process, only very light particles can be removed.
- It is a time consuming process.
- Winnowing is also very dependent on the wind and hence, isn’t a reliable technique.
Also Read: Centrifugation
Things to Remember
- Winnowing is a type of seperation method through which husk is seperated from grains.
- The first winnowing machine which was designed in the year 1737.
- The principal of winnowing is based on the difference in mass of the components of a mixture.
- Winnowing is a pollution free method and has less maintenance.
- Winnowing is effective only when there is wind blowing and thus can be unreliable at times.
Sample Questions
Ques: What is winnowing? (2 Marks)
Ans: Winnowing is a type of seperation method through which husk is seperated from grains. Winnowing can be defined as the method or technique through which lighter particles get separated from heavier particles with the help of wind.
Ques: What role does the wind play in winnowing? (2 Marks)
Ans: The mixture is taken at a height and is allowed to fall down while the wind is blowing so as the lighter components will blow off by the wind, and the heavier ones will fall down. Thus, wind has the most important role in winnowing.
Ques: Are winnowing and threshing same processes? (2 Marks)
Ans: No, winnowing and threshing are two very different processes. Winnowing is a type of seperation method through which husk is seperated from grains while in threshing the edible part of grain separated from the non-edible part.
Ques: List some advantages of winnowing. (3 Marks)
Ans: Some of the advantages of winnowing technique are given below:
- Winnowing is a crucial process in the cleaning of grains.
- It doesn’t involve any machine so it is a climate-friendly technique.
- Since there is only human activity involved so it is also cheap.
- It is a pollution free method and has less maintenance.
Ques: On what principal does the winnowing work on? (2 Marks)
Ans: The principal of winnowing is based on the difference in mass of the components of a mixture. If the mixture contains two components, one is lighter in weight and other one heavier, then they can be separated by winnowing.
Ques: What are the advantages of winnowing? (2 Marks)
Ans: Some of the disadvantages of winnowing technique are given below:
- Through this process, only very light particles can be removed.
- It is a time consuming process.
- Winnowing is also very dependent on the wind and hence, isn’t a reliable technique.
Ques: Are there any machines for winnowing? (2 Marks)
Ans: Winnowing doesn't need any type of heavy machines but some machines have been designed for it. The first machine which was designed in the year 1737 and is known by the name wind winnowing machine. The modern day machine is a combination of threshing and winnowing.
Ques: How are winnowing and sieving different? (2 Marks)
Ans: Winnowing is the process of separating lighter particles like husk from the heavier ones like grains while sieving is the process by which we can separate the substances of different sizes with the help of a sieve. Sieving has an advantage over winnowing as during this process one can also separate out liquid particles from solid while winnowing is only applicable for solid substances.
Ques: What is husk? (1 Mark)
Ans: Husk can be any one of the lighter particles like dust, cotton, lighter stones present in grains.
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