Question

Assertion: An electrostatic precipitator (ESP) is a particulate collection device that removes dust and smoke particles from flowing air using the force of an induced electrostatic charge.
Reason: An ESP is a highly efficient device as it removes 99 percent of particulate matter in the exhaust from a thermal power plant.

Answer 1

Hint: An ESP is a device which is used to separate dust and smoke particles from the air. It mainly consists of two parts – electrode wires and collecting plates. The collecting plate is used to collect the dust and smoke particles.

Complete answer:
Let us first understand what is meant by an electrostatic precipitator (ESP). An electrostatic precipitator ( also called ESP) is a device which is used in thermal power plants. We know that thermal power plants produce useful thermal energy from heating fossil fuels. In this process of production of energy, a lot of smoke and dust particles are released in the exhaust.

An ESP is a device which is used to separate dust and smoke particles from the air. It mainly consists of two parts – electrode wires and collecting plates.The electrode wires produce a high electric voltage, due to which there is a discharge of electricity (i.e. there is an electric current produced). These electrons then combine with the dust and smoke particles. We know that an electron is negatively charged. Therefore, these unwanted particles also become negatively charged.

Later, the air is passed through the collecting wire. The collecting wire is positively charged.Therefore, it attracts the negatively charged particle (duct and smoke particles). In this way, an ESP cleans air from the dust and smoke particles. An ESP is a highly efficient device as it removes 99 percent of particulate matter in the exhaust from a thermal power plant. Therefore, the given assertion and reason are correct but the reason is not the correct explanation for the assertion.

Hence, the correct option is B.

Note: Note that the collecting wire in an electrostatic precipitator must be positively charged, since a positively charged particle can attract a negative charged particle only.When we answer this type questions, we must be very careful in finding whether the reason is the correct explanation for the assertion.