Electrons and Electric Fields

Flashcards covering key vocabulary related to resistivity, resistance, and Ohm's Law from the lecture notes.

Resistivity (ρ)

A property of the material quantifying how reluctant electrons are to moving in response to an electric field, measured in Ohm-meters (Ωm).

Resistivity formula (Electric Field/Current Density)

ρ = E / J, where ρ is resistivity, E is Electric Field (V/m), and J is charge density (A/m2).

Effect of Temperature on Resistivity

Higher temperatures increase resistivity because increased particle vibration leads to more collisions, which decreases drift speed and current density.

Relationship between Potential Difference, Resistivity, and Current

ΔV = ρℓI / A, where ΔV is potential difference, ρ is resistivity, ℓ is length, I is current, and A is cross-sectional area.

Resistance (R) formula

R = ρ ℓ / A, where R is Resistance (Ω), ρ is resistivity (Ωm), ℓ is length (m), and A is cross-sectional area (m2).

Ohm's Law

ΔV = IR, stating that the potential difference across a conductor is directly proportional to the current flowing through it, with R being the constant of proportionality (resistance).

Non-ohmic materials

Materials, such as semiconductors, that do not exhibit a linear relationship between potential and current, meaning Ohm's Law does not apply to them.

Resistance

A property that characterizes a specific piece of material with defined geometry, quantifying how much it impedes the flow of electrons, measured in Ohms (Ω).

Resistivity property

If same material, resistivity does not change. It is a material's inherent opposition to electric current regardless of its shape or size, typically measured in ohm-meters (Ω·m).