PHYS 102 | Drude Model 1 - Drift Velocity

A microscopic definition of the conductivity based on the drift velocity.
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[@littleworld1952]

Your lectures are really life saving Sir

[@kabandajamir9844]

So nice the world's best teacher

[@aminnaifar4442]

Sir you are amazing! I hope you teach us on line ( if possible) some quantum statistics and some courses about semiconductors

[@Prof-Hafner]

Thanks. That is not in the current plan, but you never know. :)

[@ss-wl6zv]

Great explanation👍👍👍👍thank you😃

[@fantasyshot123]

The Drude-Model gets his name from the german physicist Paul Drude (1863-1906) who invented it. :)

[@stracci_5698]

Amazing

[@adi6516]

sir but
a x t will be final velocity before collision
shouldn't average velocity be a x t/2 as electron accelerates uniformly before collision ?
Please answer this question

[@Prof-Hafner]

ua-cam.com/video/uJ109nhN66I/v-deo.html

[@CBSdkk]

At 7:00 you set V_drift to "V_max". I would take half of the scatter time, if i am wrong please correct me.

[@Prof-Hafner]

I correct that in the next video, or it might be the one after that.

[@CBSdkk]

@@Prof-Hafner Thank you

[@anirudhdave7986]

Sir, can you please tell me that how can the average random velocity (Fermi velocity) which is the velocity of free electrons when there is no external electric field and whose value/magnitude is "zero" is greater than the drift velocity of the free electrons.

[@Prof-Hafner]

I'm not sure exactly what you mean but here are a couple of points that might help: The average velocity can be zero if the motion is random because the individual velocities add up as vectors (which can have opposite directions). That's why it averages to zero but in reality the electrons are on average moving at some speed.
To understand why the fermi velocity can be greater than drift velocity, think of it as a balloon slowly moving (drifting) along the x-axis. The individual gas atoms are moving very fast at room temperature. But they all have a slight excess velocity in the x-direction. It is basically the same with an electric field causing a current in a wire.

[@anirudhdave7986]

@@Prof-Hafner thanks a lot sir. My doubt is now clear.