[填空题]
How much energy is stored /dlya.h6 /p(c(9odr z r /qx8 uwcgb1sby the electric field between twpj .a lkeq1z8vd,c,)pah i6 v(o square plates, 8.0 cm on a side, separated by a 1.5-mm air gap? The charges on t ,vapc,i.jq p6()hl8a1ved z khe plates are equal and opposite and of magnitude $420\mu C$. J
