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(a) What is the magnitude and direction of theelectric field produced by the two

ID: 1759794 • Letter: #

Question

(a) What is the magnitude and direction of theelectric field produced by the two point charges at pointP, which is just above the surface of the Earth? 1

(b) Thinking of the Earth as a conductor, what sign of charge wouldaccumulate on the surface near point P? (This accumulatedcharge increases the magnitude of the electric field near pointP.) 3    

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In a thunderstorm, charge is separated through a complicatedmechanism that is ultimately powered by the Sun. As shown in the figure below, a simplified model of thecharge in a thundercloud represents the positive charge accumulatedat the top and the negative charge at the bottom as a pair of pointcharges. In this particular case, h = 2.2 km. (a) What is the magnitude and direction of theelectric field produced by the two point charges at pointP, which is just above the surface of the Earth? 1 (b) Thinking of the Earth as a conductor, what sign of charge wouldaccumulate on the surface near point P? (This accumulatedcharge increases the magnitude of the electric field near pointP.)

Explanation / Answer

a)    The electric field at P due to -20C is givenby               E1 = (8.90*109 N.m2/C2)(20C)/(2.2*103 m)2 The electric field atP due to 50C is given by               E2 = (8.90*109 N.m2/C2)(50C)/(10*103 m)2 The net electric field is                E = E1 - E2                  =  (8.90*109 N.m2/C2)(20 C)/(2.2*103m)2 -  (8.90*109 N.m2/C2)(50 C)/(10*103m)2 Simplifying we get the answer.    b)   postivecharge.            The net electric field is                E = E1 - E2                  =  (8.90*109 N.m2/C2)(20 C)/(2.2*103m)2 -  (8.90*109 N.m2/C2)(50 C)/(10*103m)2 Simplifying we get the answer.    b)   postivecharge.