Question

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R Assertion A: In a centrifugal pump, the function of impeller is to impart high velocity of water so that velocity head is increased. Reason R: The function of casing is to reduce velocity of water so that velocity head is reduced and converted into pressure head. In the light of the above statements, choose the most appropriate answer from the options given below

• A. Both A and R are correct and R is the correct explanation of A
• B. Both A and R are correct but R is NOT the correct explanation of A
• C. A is correct but R is not correct
• D. A is not correct but R is correct

Hint:

Functions in centrifugal pump: \[ \boxed{ \text{Impeller} \rightarrow \text{Increase velocity} } \] \[ \boxed{ \text{Casing} \rightarrow \text{Convert velocity head into pressure head} } \] Volute casing works as a diffuser.

Answer 1

The Correct Option is A

Concept: A centrifugal pump mainly consists of:
• Impeller
• Casing
• Suction pipe
• Delivery pipe The impeller transfers mechanical energy to water, while the casing converts kinetic energy into pressure energy.

Step 1: Understanding the role of impeller. The impeller rotates at high speed. Due to centrifugal action:
• Water particles move outward
• Velocity of water increases
• Kinetic energy increases Thus the impeller imparts: \[ \boxed{ \text{High velocity energy to water} } \] Hence: \[ \boxed{ \text{Assertion A is correct} } \]

Step 2: Understanding the role of casing. The casing surrounding the impeller:
• Gradually increases flow area
• Reduces water velocity
• Converts kinetic energy into pressure energy This process follows Bernoulli’s principle. Hence: \[ \boxed{ \text{Velocity head decreases and pressure head increases} } \] Therefore: \[ \boxed{ \text{Reason R is correct} } \]

Step 3: Checking whether Reason explains Assertion. The impeller first increases velocity energy. Then the casing converts this velocity energy into pressure energy. Thus:
• The impeller action and casing action are directly related
• The casing explanation correctly complements the impeller function Hence: \[ \boxed{ \text{Reason R correctly explains Assertion A} } \]

Step 4: Selecting the correct option. We conclude:
• Assertion A is correct
• Reason R is correct
• R correctly explains A Therefore: \[ \boxed{ (A) } \] is the correct answer. Final Conclusion: The impeller imparts velocity energy, and the casing converts that velocity energy into pressure energy. Hence the correct answer is: \[ \boxed{ (A) } \]