Waves

$$ f = \frac1T $$

$$ v = f\lambda $$

Refraction

$$ n_1\text{sin}(i)=n_2\text{sin}(r) $$

$$ n=\frac{c}v $$

$$ n_{2\text{ }1}=\frac{n_2}{n_1}=\frac{\text{sin}(i)}{\text{sin}(r)} $$

Mirror formulae

$$ \frac{1}{v}+\frac{1}{u} = \frac{1}{f} $$

$$ \frac{1}{v}+\frac{1}{u} = \frac{2}{R} $$

Magnification

$$ \frac{h_i}{h_o}=\frac{-v}u = M $$

Lens formulae

$$ \frac1f=\frac1v-\frac1u $$

Magnification

$$ \frac{h_i}{h_o}=\frac{v}u = M $$

Current

$$ I=\frac{q}t $$

$$ I=\frac{ne}t $$

Voltage