A, ammeter is a device for measuring current, it consumes little electric energy, and it converts the consumed electric energy into kinetic energy of ammeter pointer rotation, which conforms to the meaning of the question;

B, voltmeter is a device for measuring voltage, it consumes little electric energy, and it converts the consumed electric energy into the kinetic energy of voltmeter pointer rotation, which is in line with the meaning of the question;

C, generator is a device to generate electric energy, it is a device to convert mechanical energy into electric energy by electromagnetic induction phenomenon, which does not meet the meaning of the question;

D, the motor is a device that consumes electric energy, and converts electric energy into kinetic energy of motor rotation, which is in line with the meaning of the question.

So choose B.