Circuits

$V = IR \quad \text{(Ohm's Law)}$ $P = IV = I^2R = \frac{V^2}{R}$

• Series: R_total = R₁ + R₂ + ...; same current
• Parallel: 1/R_total = 1/R₁ + 1/R₂ + ...; same voltage

Optics

$n_1 \sin\theta_1 = n_2 \sin\theta_2 \quad \text{(Snell's Law)}$ $\frac{1}{f} = \frac{1}{d_o} + \frac{1}{d_i} \quad \text{(Thin Lens)}$

Electrochemistry

• Galvanic cells: Spontaneous, positive E°cell
• Electrolytic cells: Non-spontaneous, require external voltage
• Nernst equation: E = E° - (RT/nF)ln(Q)