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Which of motor is used for tape recorder?
Shaded pole
Hysteresis
Universal
None of above
Hysteresis
A hysteresis motor is used in a tape recorder because of its uniform torque, smooth performance, and extremely silent operation without mechanical vibrations. It is a single-phase synchronous motor whose operation depends on the phenomenon of continuous magnetic hysteresis.
A hysteresis motor is used in a tape recorder because of its uniform torque, smooth performance, and extremely silent operation without mechanical vibrations. It is a single-phase synchronous motor whose operation depends on the phenomenon of continuous magnetic hysteresis.
PhтАЛ=khтАЛтЛЕfтЛЕBmax1.6тАЛ тАФ Hysteresis power loss in the rotor
ThтАЛ=2╧АNsтАЛPhтАЛтАЛ тАФ Constant hysteresis torque developed at all speeds
When a rotating magnetic field is produced by the stator, eddy currents and magnetic hysteresis are induced in the high-retentivity rotor. Due to hysteresis loss, the rotor magnetic pole lags behind the stator magnetic pole by a hysteresis angle ╬┤, producing a constant hysteresis torque from starting up to synchronous speed.
The rotor consists of a smooth cylinder of high-retentivity hard magnetic material (such as chrome or cobalt steel) without any winding or teeth.
Noise-free and smooth operation occurs because the rotor has no teeth, slots, or mechanical vibrations during rotation.
Starting torque is equal to running torque, providing steady acceleration for precision equipment.
Extremely silent operation due to smooth non-salient rotor structure
Constant speed and uniform torque from standstill to synchronous speed
Low starting current compared to other synchronous motors
Low efficiency and low power factor
Small output capacity (usually built in fractional horsepower ratings)
Tape recorders and sound-recording equipment
Precision timing devices and electric clocks
High-quality turntables and audio equipment
Option A (Shaded pole motor) is used in small ceiling fans, hair dryers, and toy applications where low starting torque is acceptable.
Option C (Universal motor) is used in high-speed applications requiring high starting torque, such as vacuum cleaners, mixers, and portable drills.
B is correct тАФ Hysteresis motor produces constant torque and operates noise-free, making it ideal for sound equipment like tape recorders.
Always remember that for audio/timing equipment requiring noise-free, constant-speed operation, Hysteresis motor is preferred; for high-speed small home appliances, Universal motor is chosen.