for electrostatics 1: https://www.youtube.com/playlist?list=PLjMqwPTga-r1A73JDtaWhK1z-eYa53BFj
for electrostatics 2: https://www.youtube.com/playlist?list=PLjMqwPTga-r0VEMQ-m0P_7SUMft6ycMgR

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