Which of the following single-phase induction motors is generally used in time phonographs?

The correct answer is: C. Shaded pole

A shaded pole motor is a single-phase induction motor that uses a shading coil to create a rotating magnetic field. The shading coil is a copper winding that is placed around one of the poles of the stator. When current flows through the shading coil, it creates a magnetic field that opposes the main magnetic field. This causes the rotor to start rotating.

Shaded pole motors are simple and inexpensive to manufacture, making them ideal for use in low-power applications such as time phonographs. They are also very reliable and have a long lifespan.

The other options are incorrect because:

• A resistance start motor uses a resistor to start the motor. This type of motor is not as efficient as a shaded pole motor.
• A capacitor start capacitor run motor uses a capacitor to start the motor and a capacitor to run the motor. This type of motor is more efficient than a resistance start motor, but it is also more expensive.
• A universal motor can be used on both single-phase and three-phase power. This type of motor is not as common as a shaded pole motor, and it is not typically used in time phonographs.