[填空题]
A large electroscopez3q,n zl9v. o zj .0*twkqny9x is made with “l 7e6o x 7tsuf-(/kqjrseaves” that are 78-cm-long wires with tiny 24-g spheres ar(q ft-x7 6kes7oj/s ut the ends. When charged, nearly all the charge resides on the spheres. If the wires each make a $30^{\circ}$ angle with the vertical (Fig. 16–64), what total charge Q must have been applied to the electroscope? Ignore the mass of the wires. $ \times10^{-6 }\,CC$
