Physics - Current Electricity Question with Solution | TestHub

A. Drift velocity is typically on the order of $10^{-4}\text{ m/s}$, while thermal speed is around $10^5\text{ m/s}$.

B. Ohm's Law in vector form is $\vec{J}=\sigma \vec{E}$, where $\sigma$ is the conductivity, which is a constant for a given material at a given temperature. Thus, $\vec{J}\propto \vec{E}$.

C. For metals, an increase in temperature leads to increased thermal vibrations of lattice ions, causing more frequent collisions with free electrons, thereby increasing resistivity.

D. Conventional current is defined as the flow of positive charge. Since electrons are negatively charged, their drift in one direction corresponds to a conventional current in the opposite direction.