Power Systems
Non-commercial sources of energy are

 solar, wind and biomass.
None of these
 fossil fuel, hydro power and nuclear power.
  wood, animal wastes and agricultural wastes.

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Power Systems
The draft tube is provided to

 reduce the effect of water hammer.
 raise the water surface of the stream to create an artificial head.
None of these
  increase the acting head on the water wheel.

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