Class 12th Physics 2017 Set1 Delhi Board Paper Solution
Write the two processes that take place in the formation of a p-n junction. Explain with the help of a diagram, the formation of depletion region and barrier potential in a p-n junction.
During the formation to p-n Junciton two processes take place:
(i) Diffusion: There is difference in concentration of charge carriers in p-n region. The e- from n and holes from p region diffuse. Motion gives rise to diffusion current.
(ii) Drift: Diffusion of e- from n region results in ionised donor atoms (+ve). It is immobile as it is bound to surrounding atoms. Positive space charge region near junction in n region is formed.
Electrons are majority carriers in n type semiconductors and holes are majority carriers in p-type semiconductors. Loss of electrons in n region and its gain. Polarity fo potential opposes further flow of carrier i.e., it tries to attain equilibrium. As this potential is of preventive nature, so called barrier potential.
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Careful measurement of the electric field at the surface of a black box indicates that the net outward flux through the surface of the box is 8.0 × 103 N m2/C.
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A long straight horizontal cable carries a current of 2.5 A in the direction 10º south of west to 10°north of east. The magnetic meridian of the place happens to be 10º west of the geographic meridian. The earth's magnetic field at the location is 0.33 G, and the angle of dip is zero. Locate the line of neutral points (ignore the thickness of the cable). (At neutral points, magnetic field due to a current-carrying cable is equal and opposite to the horizontal component of earth's magnetic field.)
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