A.các ion dương.
B.ion âm.
C.ion dương và ion âm.
D.ion dương, ion âm và electron tự do.

A.\({u_R}\) trễ pha \(\frac{\pi }{2}\) so với \({u_C}\)
B.\({u_C}\) trễ pha \(\frac{\pi }{2}\) so với \({u_L}\)
C.\({u_L}\) sớm pha \(\frac{\pi }{2}\)so với \({u_C}\)
D.\({u_R}\) trễ pha \(\frac{\pi }{2}\) so với \({u_L}\).

A.\({\varepsilon _3} > {\varepsilon _2} > {\varepsilon _1}\)
B.\({\varepsilon _1} > {\varepsilon _2} > {\varepsilon _3}\)
C.\({\varepsilon _1} > {\varepsilon _3} > {\varepsilon _2}\)
D.\({\varepsilon _2} > {\varepsilon _3} > {\varepsilon _1}\)

A.\(\frac{{2\pi }}{3}\)
B.\(\frac{\pi }{4}\)
C.\(\frac{{3\pi }}{4}\)
D.\(\frac{\pi }{2}\)

A.0,5m.
B.1,0m.
C.2,0m.
D.2,5m.

A.\(\frac{v}{l}\)
B.\(\frac{v}{{2l}}\)
C.\(\frac{{2v}}{l}\)
D.\(\frac{v}{{4l}}\)

A.\(k{{\rm{x}}^2}\)
B.\( - k{\rm{x}}\)
C.\( - \frac{1}{2}kx\)
D.\(\frac{1}{2}k{\rm{x}}\)

A.\(2020\)
B.\(2021\)
C.\(2022\)
D.\(1\)

A.\(a =  - \omega A\sin \left( {\omega t + \varphi } \right)\)
B.\(a = {\omega ^2}Acos\left( {\omega t + \varphi } \right)\)
C.\(a =  - {\omega ^2}Aco{\rm{s}}\left( {\omega t + \varphi } \right)\)
D.\(a =  - {\omega ^2}A\sin \left( {\omega t + \varphi } \right)\)

A.\(\frac{{{U_0}}}{{\sqrt 2 \omega L}}\)
B.\(\frac{{{U_0}}}{{2\omega L}}\)
C.\(\frac{{{U_0}}}{{\omega L}}\)
D.\(0\)