[填空题]
Measurements indicate5u xie 5zx9kb6 t 1w y30bd8cjxshat there is an electric field surrounding the Earth. Its magnib81 w jyd3sc0xtude is about $150\,N/C$ at the Earth’s surface and points inward toward the Earth’s center. What is the magnitude of the electric charge on the Earth? Is it positive or negative? [Hint: the electric field outside a uniformly charged sphere is the same as if all the charge were concentrated at its center.] $ \times10^{5 }\,C$
