What are the limitations of the energy that can be obtained from the oceans?
The various forms of energy can be obtained from the ocean these are:
a. ocean thermal energy
b. wave energy and
c. tidal energy
Limitations of Tidal Energy:
i. Limited areas around the world which are suitable for building tidal dams.
ii. During high and low tides the rise and fall of sea-water is not enough to generate electricity on a large scale.
Limitations of Wave Energy:
In the world there are limits where the waves strike the shore lines with sufficient power that is sufficient to generate electric energy from the kinetic energy of the waves.
Limitations of Ocean Thermal Energy:
Ocean thermal plant involves high cost. To convert ocean thermal energy into electricity, a great variation in temperature difference of 20°C (or more) between the surface water of the ocean and deeper water is needed for operating OTEC power plants.
i. Limited areas around the world which are suitable for building tidal dams.
ii. During high and low tides the rise and fall of sea-water is not enough to generate electricity on a large scale.
Can any source of energy be pollution-free? Why or why not?
If you could use any source of energy for heating your food, which one would you use and why?
On what basis would you classify energy sources as
(a) renewable and non-renewable?
(b) exhaustible and inexhaustible?
Are the options given in (a) and (b) the same?
What is a good source of energy?
Hydrogen has been used as a rocket fuel. Would you consider it a cleaner fuel than CNG? Why or why not?
Which of the following is not an example of a bio-mass energy source?
(a) wood (b) gobar-gas
(c) nuclear energy (d) coal
What are the disadvantages of fossil fuels?
Give the names of two energy sources that you would consider to be exhaustible. Give reasons for your choices.
Name two energy sources that you would consider to be renewable. Give reasons for your choices.
How has the traditional use of wind and water energy been modified for our convenience?
Did Döbereiner’s triads also exist in the columns of Newlands’ Octaves? Compare and find out.
Why is diffusion insufficient to meet the oxygen requirements of multi-cellular organisms like humans?
What are trophic levels? Give an example of a food chain and state the different trophic levels in it.
What changes can you make in your habits to become more environment-friendly?
What is the difference between a reflex action and walking?
What is the importance of DNA copying in reproduction?
If a trait A exists in 10% of a population of an asexually reproducing species and a trait B exists in 60% of the same population, which trait is likely to have arisen earlier?
Why should a magnesium ribbon be cleared before burning in air?
Define the principal focus of a concave mirror.
You have been provided with three test tubes. One of them contains distilled water and the other two contain an acidic solution and a basic solution, respectively. If you are given only red litmus paper, how will you identify the contents of each test tube?
In evolutionary terms, can we say which among bacteria, spiders, fish and chimpanzees have a ‘better’ body design? Why or why not?
Why does distilled water not conduct electricity, whereas rain water does?
Give any two ways in which biodegradable substances would affect the environment.
What is a balanced chemical equation? Why should chemical equations be balanced?
Consider a circular loop of wire lying in the plane of the table. Let the current pass through the loop clockwise. Apply the right-hand rule to find out the direction of the magnetic field inside and outside the loop.
Give reasons why copper is used to make hot water tanks and not steel (an alloy of iron).
What are the components of the transport system in human beings? What are the functions of these components?
Imagine that you are sitting in a chamber with your back to one wall. An electron beam, moving horizontally from back wall towards the front wall, is deflected by a strong magnetic field to your right side. What is the direction of magnetic field?
Explain the following.
(a) Why is the tungsten used almost exclusively for filament of electric lamps?
(b) Why are the conductors of electric heating devices, such as bread-toasters and electric irons, made of an alloy rather than a pure metal?
(c) Why is the series arrangement not used for domestic circuits?
(d) How does the resistance of a wire vary with its area of cross-section?
(e) Why are copper and aluminium wires usually employed for electricity transmission?
What are alloys?