PMSM stands for Permanent Magnet Synchronous Motor, an AC electric motor that uses permanent magnets on its rotor to create a magnetic field. These motors are known for their high efficiency, high torque-to-weight ratio, and precise control, making them p

PMSM stands for Permanent Magnet Synchronous Motor, an AC electric motor that uses permanent magnets on its rotor to create a magnetic field. These motors are known for their high efficiency, high torque-to-weight ratio, and precise control, making them popular in applications like electric vehicles, robotics, and industrial automation. They are a type of brushless motor, meaning they lack brushes to cause wear, which results in lower maintenance.
Key characteristics
Construction: A PMSM has a stator with coils and a rotor with permanent magnets, similar to an induction motor, but without the need for wound rotor windings.
Working principle: When three-phase AC power is supplied to the stator, a rotating magnetic field is created. The rotor's magnetic poles lock in with the stator's rotating field and spin at a synchronous speed.
Performance: They offer high efficiency (up to 97%), fast acceleration, precise control, and a high power factor.
Control: Because they are not inherently self-starting, PMSMs typically require a variable frequency power supply or a controller with field-oriented control (FOC) to operate correctly.
Advantages: Key benefits include reduced power consumption, compact and lightweight structures, low noise, and high dynamic performance.
Common applications
Electric vehicles: Due to their efficiency and high power density.
Robotics and automation: For precise and quick movements.
Home appliances: Such as washing machines and air conditioners.
3D printers: For high-precision movements.
Industrial equipment: Including CNC machines and other factory automation systems.
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1. 18PYB101J Module-III Lecture-2
DEPARTMENT OF PHYSICS AND NANOTECHNOLOGY
SRM INSTITUTE OF SCIENCE AND TECHNOLOGY
18PYB101J –Physics: Electromagnetic Theory, Quantum Mechanics, Waves
and Optics
1
DEPARTMENT OF PHYSICS AND NANOTECHNOLOGY
SRM INSTITUTE OF SCIENCE AND TECHNOLOGY
21PYB101J-Electromagnetic Theory, Quantum Mechanics, Waves
and Optics
Module 3-Lecture-II
Qualitative explanations -Photoelectric effect & Compton effect,
Explanation of wave nature of particles-de Broglie hypothesis for
matter waves

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18PYB101J Module-III Lecture-2

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18PYB101J Module-III Lecture-2

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18PYB101J Module-III Lecture-2

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18PYB101J Module-III Lecture-2

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18PYB101J Module-III Lecture-2
Photoelectric effect
Thephotoelectriceffectisaphenomenoninwhichelectronsareejectedfromthe
surfaceofametalwhenlightisincidentonit.Theseejectedelectronsare
calledphotoelectrons.Itisimportanttonotethattheemissionofphotoelectronsandthe
kineticenergyoftheejectedphotoelectronsisdependentonthefrequencyofthelightthatis
incidentonthemetal’ssurface.Theprocessthroughwhichphotoelectronsareejectedfrom
thesurfaceofthemetalduetotheactionoflightiscommonlyreferredtoasphotoemission.
Thephotoelectriceffectoccursbecausetheelectronsatthesurfaceofthemetal
tendtoabsorbenergyfromtheincidentlightanduseittoovercometheattractiveforcesthat
bindthemtothemetallicnuclei.Anillustrationdetailingtheemissionofphotoelectronsasa
resultofthephotoelectriceffectisprovidedbelow.

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18PYB101J Module-III Lecture-2
Photoelectric effect
ExplainingthePhotoelectricEffect:TheConceptofPhotons
Thephotoelectriceffectcannotbeexplainedbyconsideringlightasawave.However,this
phenomenoncanbeexplainedbytheparticlenatureoflight,inwhichlightcanbevisualizedas
astreamofparticlesofelectromagneticenergy.These‘particles’oflightarecalledphotons.
TheenergyheldbyaphotonisrelatedtothefrequencyofthelightviaPlanck’sequation:
E=h??????=hc/λ

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18PYB101J Module-III Lecture-2
Photoelectric effect
Where,
E denotes the energy of the photon
h is Planck’s constant
??????denotes the frequency of the light
c is the speed of light (in a vacuum)
λ is the wavelength of the light
Thus,itcanbeunderstoodthatdifferentfrequenciesoflightcarryphotonsofvarying
energies.Forexample,thefrequencyofbluelightisgreaterthanthatofredlight(the
wavelengthofbluelightismuchshorterthanthewavelengthofredlight).Therefore,the
energyheldbyaphotonofbluelightwillbegreaterthantheenergyheldbyaphotonofred
light.

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18PYB101J Module-III Lecture-3
de-Broglie Concept of Dual Nature
⮚The universe is made of Radiation (light) and matter (particles). The light exhibits the dual
nature (i.e.,) it can behaves both as a wave (Interference, diffraction phenomenon) and as a
particle (Compton effect, photo-electric effect etc).
⮚Since the nature loves symmetry, in 1924 Louis de-Broglie suggested that an electron (or)
any other material particle must exhibit wave like properties in addition to particle nature.
⮚The waves associated with a material particle are called as Matter waves.

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18PYB101J Module-III Lecture-3