A.\(\frac{\pi }{4}\).
B.\(\frac{\pi }{2}\).
C.\(\frac{\pi }{3}\).
D.\(\frac{\pi }{6}\).

A.31 cm.
B.19 cm.
C.22 cm.
D.28 cm.

A.16,2 kW.h.
B.4,5 kW.h.
C.4500 kW.h.
D.16200 kW.h.

A.0,1π rad/s.
B.400 rad/s.
C.0,2π rad/s.
D.20 rad/s.

A.3 cm.
B.5 cm.
C.7 cm.
D.1 cm.

A.25 cm.
B.9 m.
C.25 m.
D.9 cm.

A.1:00 AM
B.2:00 AM
C.\(\sqrt 2 \,\,A\).
D.\(2\sqrt 2 \,\,A\).

A.0,8.
B.0,7.
C.0,5.
D.0,9.

A.lệch pha \(\dfrac{\pi }{2}\).
B.cùng pha.
C.lệch pha \(\dfrac{\pi }{4}\).
D.ngược pha.

A.\(B = 2\pi {.10^7}\frac{R}{I}\).
B.\(B = 2\pi {.10^{ - 7}}\frac{R}{I}\).
C.\(B = 2\pi {.10^7}\frac{I}{R}\).
D.\(B = 2\pi {.10^{ - 7}}\frac{I}{R}\).