6.
在平面直角坐标系\(x0y\)中,已知点\(A(- \sqrt {2},0)\),\(B( \sqrt {2},0)\),\(E\)为动点,且直线\(EA\)与直线\(EB\)的斜率之积为\(- \dfrac {1}{2}\).
\((\)Ⅰ\()\)求动点\(E\)的轨迹\(C\)的方程\(;\)
\((\)Ⅱ\()\)设过点\(F(1,0)\)的直线\(l\)与曲线\(C\)相交于不同的两点\(M\),\(N.\)若点\(P\)在\(y\)轴上,且\(|PM|=|PN|\),求点\(P\)的纵坐标的取值范围.