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Physics II - B09

TABLE OF CONTENTS

Electric Current

Current and Drift Speed

$\displaystyle I_{avg} = \frac{\Delta Q}{\Delta t} = \frac{n.q}{\Delta t} = \frac{\frac{n}{V}.V.q}{\Delta t} = n.A.q.v$

  • n is the number of mobile charge carriers per unit volume

Current Density

Ohm’s Law

\[J = \sigma.E \to \frac{I}{A} = \sigma.\frac{\Delta V}{l} \to \frac{\Delta V}{I} = \frac{l}{\sigma.A} = R\]

Resistance (Điện trở)

Resistivity (Điện trở suất)

\[\vec a = \frac{q.\vec E}{m_e} \to v_d = \frac{q.\vec E}{m_e}.t\] \[J = n.q.v = \frac{n.q.E}{m_e}.\tau = \sigma . E\]

  • Note, according to this classical model, the conductivity and the resistivity do not depend on the strength of the field.

Resistance and Temperature

Super Conductor (Vật liệu siêu dẫn)

Electric Power (Joule - Lenz)

Other references