Current Electricity — Important Questions

Length of the conductor, Cross-sectional area of the conductor, Material of the conductor (resistivity), Temperature of the conductor

Resistance depends on length (R ∝ l), cross-sectional area (R ∝ 1/A), material properties (resistivity ρ), and temperature. The color of the conductor does not affect its electrical resistance.

Very low (few mm/s)

Drift velocity is the average velocity of electrons in a conductor and is typically very small (order of mm/s or cm/s), much slower than their random thermal motion.

I = neAvd

Current I = neAvd, where n is the number density of charge carriers, e is the charge of an electron, A is the cross-sectional area, and vd is the drift velocity.

Terminal voltage of the cell, Current delivered by the cell, Power delivered to external circuit, Maximum current the cell can deliver

Internal resistance affects terminal voltage (V = ε - Ir), current delivered, power to external circuit, and maximum current. However, EMF is an intrinsic property of the cell and is not affected by internal resistance.