In a thundercloud, the bottom of the cloud becomes negatively charged. Since the Earth is a reasonably good conductor, this induces a positive charge on the ground below, generating an electric field. 1) The electric field between the ground and a typical thundercloud is about 2000 N/C. (a) Sketch the electric field between the cloud and the Earth. (b) What is the charge per unit area of the bottom surface of the cloud and of the Earth? (You may assume the thundercloud is roughly flat on the bottom, and is much closer to the Earth than it is wide.)
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These arrows represent the direction and magnitude of the electric field. Since the electric field is directed from positive to negative charges, the arrows should point downwards towards the Earth. The length of the arrows can represent the magnitude of the Show more…
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Figure 17.31 b shows a thundercloud before a lightning strike has occurred. The bottom of the thundercloud and the Earth's surface might be modeled as a charged parallel plate capacitor. The base of the cloud, which is roughly parallel to the Earth's surface, serves as the negative plate and the region of Earth's surface under the cloud serves as the positive plate. The separation between the cloud base and the Earth's surface is small compared to the length of the cloud. (a) Find the capacitance for a thundercloud of base dimensions $4.5 \mathrm{km}$ by $2.5 \mathrm{km}$ located $550 \mathrm{m}$ above the Earth's surface. (b) Find the energy stored in this capacitor if the charge magnitude is $18 \mathrm{C}$.
In a thunderstorm, charge is separated through a complicated mechanism that is ultimately powered by the Sun. A simplified model of the charge in a thundercloud represents the positive charge accumulated at the top and the negative charge at the bottom as a pair of point charges. (a) What is the magnitude and direction of the electric field produced by the two point charges at point $P$, which is just above Earth's surface? (b) Treating Earth as a conductor, what sign of charge would accumulate on the surface near point $P ?$ (This accumulated charge increases the magnitude of the electric field near point $P_{0}$ )
Storm clouds may build up large negative charges near their bottom edges. The earth is a good conductor, so the charge on the cloud attracts an equal and opposite charge on the earth under the cloud. The electric field strength near the earth depends on the shape of the earth's surface, as we can explain with a simple model. The top metal plate in Figure $\mathrm{P} 20.37$ has uniformly distributed negative charge. The bottom metal plate, which has a high point, has an equal and opposite charge that is free to move. A. Sketch the two plates and the region between them, showing the distribution of positive charge on the bottom plate. b. Complete your diagram by sketching electric field lines between the two plates. Be sure to note the direction of the field. Where is the field strongest? c. Explain why it is more dangerous to be on top of a hill or mountain during a lightning storm than on level ground.
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