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(a) Comment on the pattern in which all ...

(a) Comment on the pattern in which all communities undergo a change in composition and structure with changing environmental conditions.
(b) Explain 'Climax community' and 'sere'.
Differentiate between primary and secondary succession with examples.

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(a) This change is orderly and sequential parallel with the changes in the physical environment. The gradual and fairly predictable change in the species composition of a given are is called ecological succession.
(b) Climax community : Changes lead a community that is in a near equilibrium with the environment and that is a climax community
'sere' : The entire sequence of communities that successively change in a given area.
(c)
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The Betatron was the first important machine for producing high energy electrons. The action of the betatron depends on the same fundamental principle as that of the transformer in which an alternating current applied to a primary coil induces an altermating current usually with higher or lower voltage in the secondary coil. In the betatron secondary coil is replaced by a doughnut shaped vacuum chamber.Electron produced in the doughnut from a hot filament, are given a preliminary acceleration by the application of an electric field having potential difference of 20 kV to 70 kV , when an alternating magnetic field is applied parallel to the axis of the tube, two effects are produced (1) an electromotive force is produced in the electron orbit by the changing magnetic flux that gives an additional energy to the electrons (2) a radial force is produced by the action of magnetic field whose direction is perpendicular to the electron velocity. Which keeps the electron moving in a circular path. Conditions are arranged such that the increasing magnetic field keeps the electron in a circular orbit of constant radius. The mathematical relation between the betatron parameters to ensure the above condition is called BETATRON condition. If the orbit radius of the circular path traced by the electron is R , magnetic field is B , speed of the electron is v , mass of the electron is m , charge on the electron is e and phi is the flux within the orbit of radius R . Then answer the following questions based on the above comprehension. What is the BETATRON condition ?

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The Betatron was the first important machine for producing high energy electrons. The action of the betatron depends on the same fundamental principle as that of the transformer in which an alternating current applied to a primary coil induces an altermating current usually with higher or lower voltage in the secondary coil. In the betatron secondary coil is replaced by a doughnut shaped vacuum chamber.Electron produced in the doughnut from a hot filament, are given a preliminary acceleration by the application of an electric field having potential difference of 20 kV to 70 kV , when an alternating magnetic field is applied parallel to the axis of the tube, two effects are produced (1) an electromotive force is produced in the electron orbit by the changing magnetic flux that gives an additional energy to the electrons (2) a radial force is produced by the action of magnetic field whose direction is perpendicular to the electron velocity. Which keeps the electron moving in a circular path. Conditions are arranged such that the increasing magnetic field keeps the electron in a circular orbit of constant radius. The mathematical relation between the betatron parameters to ensure the above condition is called BETATRON condition. If the orbit radius of the circular path traced by the electron is R , magnetic field is B , speed of the electron is v , mass of the electron is m , charge on the electron is e and phi is the flux within the orbit of radius R . Then answer the following questions based on the above comprehension. What is the value of (d(m|vecv|))/(dt) ?

XII BOARD PREVIOUS YEAR PAPER ENGLISH-XII BOARDS-COMPTT
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  5. Write the function of a Bioreactor.

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  9. Plants like potato, sugarcane do not require seeds for producing new p...

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  11. Name the first antibiotic discovered and by whom.

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