Class 12 Physics - Ray Optics

1. Total Internal Reflection (TIR)

Conditions:

1. Ray moves from denser to rarer medium.
2. Angle of incidence > Critical Angle ($i > i_c$).Application: Optical Fibers (Zero loss transmission).

2. Lens Maker's Formula

$$\frac{1}{f} = (\mu - 1) \left( \frac{1}{R_1} - \frac{1}{R_2} \right)$$

3. Prism Formula

$$\mu = \frac{\sin \frac{A + \delta_m}{2}}{\sin \frac{A}{2}}$$ Where $\delta_m$ is the angle of minimum deviation.

4. Optical Instruments

• Compound Microscope: Large magnification. Two lenses (Objective and Eyepiece).
• Astronomical Telescope: Large focal length objective to gather more light.
  • Magnifying Power $M = \frac{f_o}{f_e}$ (at normal adjustment).

Practice the Ray Diagrams for Telescope! Half marks are for arrows. 🔭💡