Effective Mass of Electrons and Holes

[@arjunmalik9963]

I am from India , honestly speaking Ma'am your explanation is good,i helps me alot , please create more and more video

[@ceramicitbhu]

I find it cheap and distasteful trick when video posters puts the extremely garish and flashy bars near places where one cant close them and/or are inconvenient to close. Overall your video was good, I would keep the good content coming but lay off the click-baitey bars in video hindering the video.

[@yuvrajsingh8609]

Why incomplete video bhai poora smjha jaate to mja aata

[@rajdeepmitra2561]

Why have you uploaded an incomplete video?

[@kgsubhash]

good expln. helped me a lot

[@OfficialAnarchyz]

we TEEEEENNNNNDDD to give

[@skyishigh7775]

Really!!!it should be an advertisement in other KZbin video...

[@shashanksahu2326]

Nice, but video is incomplete.

[@dinakardanny548]

do holes have mass??

[@AJ-fo3hp]

www.researchgate.net/post/Why_effective_mass_of_hole_is_greater_than_electron The concept of effective mass follows from physicists' love for simple relations such as Ohm's law (current density = conductivity x electric field intensity) or Newton's second law of motion (acceleration = force / mass). For a free electron, the mass in the latter is just the electron mass. But, if one wants to write a similar relation for a charge carrier in a crystal lattice, the situation changes. Going through the math (see any solid state physics textbook) allows you to write F = m x a, where the force is charge x electric field, but the mass is no longer the mass of the electron, but reflects the curvature of the conduction band bottom (for electrons) or valence band top (for holes), as it is inversely proportional to the second derivative of the energy as a function of k. This is the so-called effective mass. Again, physicists like simple things, so one often expresses the effective mass as a constant x electron mass, although this has very little (or nothing) to do with the actual physics of the situation. Hence: it is just a practical mathematical construction aimed at simplifying equations (in a similar manner as the reciprocal lattice, for example). The hole itself is also a mathematical construction helping us to avoid using negative values for mass in the simple equations (the effective mass for conduction occurring through the unoccupied electron states in the valence band would be negative, if we didn't invert the charge). In the majority of cases, the top of the valence band is clearly "flatter" than the bottom of the conduction band. From this follows that the hole effective mass is often larger than the electron effective mass. The top of the valence band tends to be flatter due to the asymmetry of the situation: you are talking about the highest occupied states for electrons. The bottom of the conduction band is formed by the lowest unoccupied states.

[@mrsandman4769]

@zeeshan arif 8 years late but holes have negative effectve mass !

[@untold_cambridge]

good strt but incomplete

[@Jayvaid]

video stopped without even giving full explanation

[@kayrstar8965]

voice and stuff is irrelevant ,but ur prsentation is just throwing facts ,thats not teaching at all(I would have visited my school if i wanted this quality of shiet and not youtube)

[@animeshsingh1307]

Mass can be negative? Seriously?

[@anassaifi7613]

Voice is so irritating

[@arathy977]

this is the most irritating voice i have ever heard......after my teacher's , of course.

[@luckykashyap9993]

My kind of person

[@Cardmaster99]

Im so sorry but your voice makes it near impossible to concentrate.

[@adityapratap2444]

voice quality is very bad ..I can't hear that voice....apart from the voice concept explanation is very very bad .

[@aziz8]

move on and save your time. video incomplete. link will take a site when you have to pay to watch. Let alone how it is hard to concentrate with the way she speaks. keep looking.

[@deuce-way1440]

i stopped listening when you said negative mass. stop trolling