If total head available at the inlet of pipe and f1 is the loss of head due to friction in the pipe, the maximum efficiency of transmission of power (ηmax) is

ANS:B - 2/3

The maximum efficiency of transmission of power (ηmax​) in a pipe occurs when the loss of head due to friction (f1) is equal to one-third of the total head available at the inlet of the pipe, not 1/2 as previously mentioned. Here's the explanation: The efficiency of power transmission (η) in a pipe system is given by: η=H−f1/H​​ Where:

• H is the total head available at the inlet of the pipe.
• f1​ is the loss of head due to friction in the pipe.

For maximum efficiency (ηmax​), we want to maximize η. This occurs when f1​ is minimized relative to H. In this case, the maximum efficiency of transmission of power (ηmax​) occurs when f1​ is one-third of H, because it's the point where the friction losses are balanced with the available head, maximizing the efficiency. Therefore, the correct answer is: 2/3