Question

The clouds consist of charged particles of water dispersed in the air. Some of them are positively charged, others are negatively charged. When positively charged clouds come closer, they cause lightning and thundering whereas when positive and negative charged colloids come closer, they cause heavy rain by aggregation of minute particles. It is possible to cause artificial rain by throwing electrified sand or silver iodide from an aeroplane and thus, coagulation the mist hanging in the air.

Electrical chimneys are made on the principle of :

• A. electro-osmosis
• B. electrophoresis
• C. coagulation
• D. all the above

Answer 1

The correct option is B electrophoresis

Electrophoresis or Cataphoresis : The colloidal particles carry an electric charge. The colloidal solution is taken in a U- tube and two platinum electrodes are dipped in the sol as shown in the figure. The current is then switched on. On closing the circuit, it is found that colloid particles move to the oppositely charged electrode and on reaching that electrode they get discharged. As soon as the charge of the particles is neutralized, they aggregate and settle down. This movement of colloid particles in electric field is known as electrophoresis in case of the true solutions.
Electric chimney used in modern kitchen is based on electrophoresis. Smoke particles get attracted towards charged electrode.