Question

Statement (I): In Impulse turbines, pressure change occurs only in the nozzles of the machine. The pressure of liquid does not change while flowing through the rotor of the machine.

Statement (II):  The pressure of liquid change while it flows through the rotor of the machine in Reaction turbine. 
1. Both statement (I) and Statement (II) are individually true and Statement (II) is the correct explanation of Statement (I)
2. Both Statement (I) and Statement (II) are individually true but statement (II) is not the correct explanation of Statement (I)
3. Statement (I) is true but Statement (II) is false
4. Statement (I) is false but Statement (II) is true

Answer 1

Correct Answer - Option 2 : Both Statement (I) and Statement (II) are individually true but statement (II) is not the correct explanation of Statement (I)

Explanation:

An important criterion to consider while classifying hydraulic turbines is whether or not the pressure of liquid changes while it is flowing through the rotor of the turbine. Based on the pressure change, hydraulic turbines can be categorized into two types:

• Impulse turbines – The pressure of liquid does not change while flowing through the rotor of the machine.
• In impulse turbines, pressure change occurs only in the nozzles of the machine. One example of an impulse turbine is the Pelton wheel. Hence, the statement I is true.
• Reaction turbines – The pressure of liquid changes while flowing through the rotor of the machine.
• Hence statement II is also true. The change in fluid velocity and reduction in its pressure causes a reaction on the turbine blades; hence the probable derivation of the name reaction turbine. Francis and Kaplan turbines fall into this category.

So, as we can see both the statements I and II are correct. But statement II is not the correct explanation of statement I. Hence, the correct option is option (2).