L L i(t o(t) U(t)= 山山 e c0s90°+jsin90°=j if u=x2y cos(at+9) y leads I by90° i=√2cos(or+) joL--impedance( 2) 2V cos(at +9) (阻抗) QL√2Isin(or+p) oL--inductor reac tan ce =o√2 I cos(ar+g+90°) (感抗) 1∠9=joLI∠q V=jaLL : dt di ( t ) = L V = jLI • • V = j L I e j j j = + = cos90 sin90 90 V leads I by 90 • • jL − −impedance ( ) (阻抗) L − −inductor reac tan ce (感抗) + ( t ) − i ( t ) L •I + − •VL •I •V 2 cos( ) 2 cos( ) = + = + i I t i f V t 2 sin( ) 2 cos( ) = − + + L I t V t = L 2 I cos(t + + 90 )