The total electric charge in a closed system remains constant. Charge can only be transferred, not created or destroyed.

A material with free electrons that allows charge to flow easily (e.g., metals).

A material with tightly bound electrons that resists charge flow (e.g., rubber, plastic).

The rate of charge flow, measured in Amperes: $I = \frac{\Delta Q}{\Delta t}$.

Opposition to current flow, measured in Ohms: $R = \frac{\rho L}{A}$.

Electric potential (voltage) is the potential energy per unit charge: $V = \frac{U}{q}$.

Conductors: Allow free flow of charge, low resistance, high electron mobility. | Insulators: Restrict charge flow, high resistance, low electron mobility.

Electric Potential (V): Property of the electric field. | Electric Potential Energy (U): Property of a charge in the electric field.

Series Circuits: Current is the same, resistances add directly, voltage drops add up. | Parallel Circuits: Voltage is the same, resistances add as reciprocals, current splits.

Attractive Forces: Occur between opposite charges (positive and negative). | Repulsive Forces: Occur between like charges (positive and positive, or negative and negative).

Reflection: Light bounces off a surface, angle of incidence equals the angle of reflection. | Refraction: Light bends as it passes through a medium, described by Snell's Law.

Charge is redistributed until they reach equilibrium, conserving total system charge (charging by conduction).

Charge separation occurs in the neutral object (induction).

The wire experiences a force: $F = ILB \sin(\theta)$.

An electric field is induced (electromagnetic induction).

Refraction occurs, and the light bends according to Snell's Law: $n_1 \sin(\theta_1) = n_2 \sin(\theta_2)$.

Photons are emitted or absorbed, with energy $E = hf$.