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Consider the following statements about torque in synchronous motors.

I. The torque in a synchronous motor is produced only when the rotor is locked into synchronism.

II. The torque is directly proportional to the sine of the load angle (δ).

III. Synchronous motor develops starting torque proportional to the power input.

IV. Maximum torque occurs at δ = 180°.

Which of the above statements are correct?

Why are instrument transformers used with a wattmeter for high-power AC measurements?

Which crystal structure is specifically associated with ferrite iron (α-iron), a ferromagnetic material?

What is the purpose of a Buchholz relay in transformer protection?

In a properly biased PNP transistor operating in active region, the emitter terminal is _______.

A PNP transistor is operating in active region. If the emitter voltage decreases such that the emitter becomes less positive than the base while the biasing condition of the collector-base junction remains unchanged, the transistor will enter _______.

Protection of transmission lines using differential pilot wire protection provides:

The hypotenuse of the power triangle represents which type of power?

The tapping in an auto transformer is used to:

What is a typical starting torque characteristic of a shaded pole induction motor?