In electronics it is customary to define the potential of ground (thinking of the earth as a large conductor) as zero. Is this consistent with the fact that the earth has a net electric charge that is not zero? (Refer to Exercise 21.28.) 21.28 Electric Field of the Earth. The earth has a net electric charge that causes a field at points near its surface equal to 150 N/C and directed in toward the center of the earth. (a) What magnitude and sign of charge would a 60-kg human have to acquire to overcome his or her weight by the force exerted by the earth’s electric field? (b) What would be the force of repulsion between two people each with the charge calculated in part (a) and separated by a distance of 100 m? Is use of the earth’s electric field a feasible means of flight? Why or why not?
30 August 2017 Earth Sun Relationship (Cont’d) ● Tilt of arth = 23.5° ● Earth’s revolution around the associated weather ○ Aphelion - Earth is farthest from the Sun; gives N Hemisphere warm weather and S Hem old temperatures Occurs roughly uly ) ○ Perihelion - Earth is closest to the Sun; gives N Hem cold weather and S Hem warm w eather occurs roughly January 3) ○ The Summer Solstice - June 21, N Hem is tilted towards the Sun, getting the most radiation out of the year; Subsolar point is 23.5° N; North Pole gets 24 hrs of aylight ○ Autumnal Equinox - Sept 22, neither hemisphere is more so tilted towards the Sun; Sub-solar point is at equator ○ Winter Solstice - Dec 21, S Hem is tilted towards the Sun, now beginning their “summer”; Subsolar point is 23.5° S; South Pole gets 24hrs of daylight ○ Vernal Equinox - March 20, neither hemisphere is tilted towards the Sun; Sub-solar point quator ● Changing seasons are ue o ○ the tilt of the earth’s axis ○ its pat round the Sun ○ the rotation of the Earth ab
