What are the raw materials used for making biogas?

The major component of biogas is :

The fuel which is not obtained from biomass is:

How has the traditional use of energy of flowing water been modified for our convenience?

Why is the copper tube of a solar water heater painted black from outside?

Fill in the following blanks with suitable words:

(a) Biomass is another form in which .......... energy manifests itself.

(b) Tidal waves build up and recede .............. a day.

A certain form of energy is available due to the difference in the temperature of water at the surface of the ocean and its deeper levels.

(a) Name the form of energy.

(b) Is this energy ultimately derived from the sun or not?

(c) Explain how this form of energy can be converted into electricity.

(d) What is the minimum temperature difference in water at the surface of ocean and its deeper level which is required to operate power plants based on this energy ?

State two advantage of producing hydroelectricity.

What type of energy is possessed by flowing water?

Flowing water can rotate a turbine. Which type of energy is used up by the turbine?

At a hydro power plant: