A hollow metal sphere has inner radius a and outer radius b. The hollow sphere has charge +2 Q. A point charge + Q sits at the center of the hollow sphere.

Determine the magnitude of the electric field in the region r≤a.

Explanation:

"Determine the magnitude of the electric field in the region r<a."

From Gauss' Law:

E(4?r^2) = +Q/?o

E = +Q/[(4??o)r^2]

"Determine the magnitude of the electric field in the region a<r<b"

The electric field inside of a conductor (with no current) is zero.

-first use of geothermal energy occurred more than 10,000 years ago in north america by american paleo-indians

-the first industrial use of geothermal energy began near pisa, italy in late 18th century

-in 1904, italian scientist piero ginori conti invented the first geothermal electric power plant in which steam was used to generate the power

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-however, in 1946 first ground-source geothermal heat pump installed at commonwealth building in portland, oregon

-during the 1960’s, pacific gas and electric began operation of first large scale geothermal power plant in san francisco, producing 11 megawatts

-in 1973, when oil crisis began many countries began looking for renewable energy sources and by 1980’s geothermal heat pumps (ghp) started gaining popularity in order to reduce heating and cooling costs

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