Question

What is the basic principle of Cottrell’s precipitator?
(A) Le-chatelier’s principle
(B) Peptization
(C) Neutralisation of charge on colloidal particles
(D) Scattering of light

Answer 1

Hint:As we know that Cottrell’s precipitator is a filtration device which basically removes the fine particles such as smoke and dust from a flowing industrial waste gas by the use of a force of an induced electrostatic charge where dust and smoke are attracted towards positively charged wire electrode.

Complete answer:As we have learnt that Cottrell’s precipitator is basically a filtration device and it neutralises the charge present on the colloidal particles. It was invented by Frederick Gardner Cottrell for the purpose of elimination of air pollution. It was known as the first electrostatic precipitator because it was the first device which was used for charging particles and collecting them with the help of an electrostatic attraction force. He first used this device to collect the mist of sulphuric acid and lead oxide fumes which were emitted from various activities of making acids and smelting. Now, let us talk about the working of Cottrell’s precipitator, it works on the basic principle where dirty flue gas is forced which escapes the smokestack past the two electrodes in the form of metal, bars or plates inside a pipe. As the dirt particles move passing the pipe, it attains a negative charge and the second electrode present at the higher end of the pipe has a positive charge which attracts the soot particles, sticks there and precipitates there.So we can say that the basic principle of the Cottrell’s precipitator is the neutralisation of charge on colloidal particles or in other words we can say that Cottrell’s precipitator works on the principle where removal of dust particles from the industrial waste gases takes place by simply attracting them to charges grids or wires or plates.

Therefore, the correct answer is (C) option.

Note:Remember that Le-chatelier’s principle is related to equilibrium of the reaction where the temperature, pressure, concentration and volume possess changes to achieve a new equilibrium state and scattering of light is related to the movement of particles or radiations in terms of light and sound to deviated from a straight trajectory by localised non-uniformities in medium via which they pass.