When the gross head of a hydroelectric project is 80 m and total head loss due to friction and turbulence is 5 m, the net head available at the turbine equals —

• 75 m

• 80 m

• 85 m

• 70 m

If the penstock length increases while diameter remains constant, the water-hammer pressure will —

• Increase linearly

• Decrease

• Remain same

• First increase then drop

In a reservoir, water stored below the invert level of the lowest outlet cannot be used for power generation. This portion is called —

• Live storage

• Dead storage

• Surcharge storage

• Valley storage

When a canal and a natural drain meet approximately at the same level, the suitable cross-drainage work adopted is —

• Super passage

• Aqueduct

• Level crossing

• Siphon aqueduct

The type of turbine used where the head is more than 250 m and discharge is comparatively low is —

• Francis turbine

• Pelton wheel

• Kaplan turbine

• Propeller turbine

A gravity dam resists the water pressure mainly by its self-weight.

• True

• False

A forebay tank in a hydroelectric plant is mainly provided to store surplus energy of the generator during low load.

• True

• False

Assertion (A): A surge tank is provided between penstock and turbine. Reason (R): It absorbs sudden excess pressure caused by rapid valve closure.

• Both A and R true; R is correct explanation of A

• Both A and R true; R not correct explanation

• A true but R false

• Both A and R false

The irrigation method adopted when the water level of the source is lower than the command area is called __________.

The time interval between the first watering before sowing and last watering before harvest is known as __________.