(a) A black surface absorbs more heat or energy as compared to white or reflecting surface under same condition
(b) A solar cell is a device which converts solar energy directly into electric energy. Silicon and germanium are the two most commonly used materials for making solar cells.
(c)
(d) Sunlight is concentrated on black painted pipes (filled with water) with the help of concave reflectors. Due to solar heat, water starts boiling and then changes into steam. The steam so produced rotates a steam turbine which drives a generator to produce electricity. A 50kW solar thermal power plant is being installed at the Twal Pahari Premises of the Solar Energy Centre, Gurgaon (Haryana).
(e) 2000 C
(f) The four possible mistakes in the construction and operation of the cooker are:
(i) The interior of solar cooker might not have been blackened,
(ii) Plastic cover might have been used instead of glass cover,
(iii) The cooker might not have been properly insulated,
(iv) The cooker utensils might not have been blackened.
Fossil fuels were formed due to high pressure, heat and the action of anaerobic bacteria of fossils for million of years. These fuels were made form the fossils of plants and animals buried deep in the Earth.
Melting point of tungsten is very high so it is used for making filament of electric lamps
(i)Methane
(ii)Hydrogen
(iii) Sulphur dioxide and Nitric oxide.
To produce nuclear energy, a heavy nucleus is bombarded with a low energy neutron. In this process, it splits into two lighter nuclei with a tremendous release of energy which can be utilized to boil water to run turbines.
The major hazard of nuclear power generation is the storage and disposal of nucleus wastes because they are radioactive
(a) No harmful gases are produced on burning charcoal
(b) No residue is left after it has burnt itself out.
(c) It has a higher calorific value.
(a) A good fuel which gives more energy per unit volume or mass
(b) It is easy to store and transport
(c) It should generate less pollution
(d) It should be harmful to the surroundings
(a) True
(b) False, Ocean thermal energy is due to temperature difference at different level
(c) True
(d) false as it is present
(e) False
(f) false
