Correct Answer - Option 2 : Doubled

__Concept-__

Head loss due to flow in a pipe can be given as \({h_L} = \frac{{fL{V^2}}}{{2gd}}\)

Here f = friction factor, L = Length of pipe, V = Velocity of flow

g = Acceleration due to gravity, d = diameter of pipe

__Calculation-__

The velocity of flow as well as the diameter of the flowing pipe are respectively doubled

So

\({h_{11}} = \frac{{fLv_1^2}}{{2g{d_1}}}\)

\({h_{12}} = \frac{{4fLv_1^2}}{{4g{d_1}}}\)

\(\frac{{{h_{l1}}}}{{{h_{l2}}}} = 0.5\;\)

**So new head loss will be two times the initial head loss.**

If the velocity of flow as well as the diameter of the flowing pipe are respectively doubled, the **head loss thereafter be doubled.**