Electricity — Circuits & Electromagnetic Concepts

Coulomb's Law: F = kq₁q₂/r² (k = 9×10⁹ N·m²/C²)

Electric field: E = F/q = kQ/r²

Field lines go from positive to negative charges

Ohm's Law: V = IR

V = voltage (volts), I = current (amps), R = resistance (ohms)

Power: P = IV = I²R = V²/R

Resistors in series: R_total = R₁ + R₂ + R₃ (same current)

Resistors in parallel: 1/R_total = 1/R₁ + 1/R₂ + 1/R₃ (same voltage; total resistance decreases)

Capacitors: Store charge. C = Q/V. In parallel: C adds. In series: 1/C adds.

Magnetic force: F = qvB sinθ

Moving charge in magnetic field experiences force perpendicular to both velocity and field

Biological relevance: Electrocardiogram (ECG) measures electrical activity of heart. Nerve conduction uses ion gradients to create electrical signals. MRI uses magnetic fields.

Reference:

Wikipedia: Electromagnetism

https://en.wikipedia.org/wiki/Electromagnetism