Introduction:
The UPSC Physics optional subject covers a vast range of topics, including various case studies and real-life examples. These case studies and examples help in understanding the practical applications of physics concepts and theories. Here are a few important case studies and real-life examples that you should be aware of for the UPSC Physics optional subject:

1. Rutherford's Gold Foil Experiment:
- In this experiment, Ernest Rutherford bombarded a thin gold foil with alpha particles.
- The majority of alpha particles passed straight through the foil, while a small fraction were deflected at large angles.
- This experiment led to the discovery of the atomic nucleus and the concept of the Rutherford model of the atom.

2. The Doppler Effect:
- The Doppler effect is the change in frequency or wavelength of a wave as observed by an observer moving relative to the source of the wave.
- This effect can be observed in various real-life situations, such as the change in pitch of a siren as an ambulance approaches and then moves away.

3. Hubble's Law:
- Edwin Hubble's observations of distant galaxies showed that they were moving away from us at speeds proportional to their distances.
- This led to the formulation of Hubble's Law, which states that the velocity at which a galaxy is moving away from us is directly proportional to its distance.

4. Photoelectric Effect:
- The photoelectric effect refers to the emission of electrons from a material when light of a certain frequency is incident upon it.
- This phenomenon has various practical applications, such as in solar cells and photodiodes.

5. Superconductivity:
- Superconductivity is a phenomenon where certain materials exhibit zero electrical resistance when cooled below a critical temperature.
- This has numerous applications, including in MRI machines, particle accelerators, and power transmission lines.

6. Quantum Teleportation:
- Quantum teleportation is a process that allows the transfer of quantum information from one location to another.
- This concept has been experimentally demonstrated, showcasing the potential of quantum mechanics in advanced communication systems.

Conclusion:
Understanding case studies and real-life examples in physics is crucial for the UPSC Physics optional subject. These examples illustrate the practical applications of various physics concepts and theories. Familiarizing yourself with these case studies and examples will enhance your understanding and help you answer questions effectively in the UPSC examination.