[填空题]
A point charge of mass 0.210 mw5l k/s2+oo(zwc1ts) lgz9 skg,u blh* vgihd:8;l/1hl k l:d9l and net charge $+0.340\,\mu C$, hangs at rest at the end of an insulating string above a large sheet of charge. The horizontal sheet of uniform charge creates a uniform vertical electric field in the vicinity of the point charge. The tension in the string is measured to be 5.67 N. Calculate the magnitude and direction of the electric field due to the sheet of charge (Fig. 16–67). $ \times10^{7 }\,N/C$
