Chapter 19: Dawn of Modern Physics

This is a ninth chapter of the book Physics 12 published by Punjab Curriculum and Textbook Board, Lahore, Pakistan.

After studying this chapter, the students will be able to:

• Distinguish between inertial and non-inertial frames of references.
• Describe the postulates of special theory of relativity and its results.
• Understand the NAVASTAR navigation system.
• Understand the concept of black body radiation.
• Understand and describe how energy is distributed over the wavelength range for several values of source temperature.
• Know Planck's assumptions.
• Know the origin of quantum theory.
• Show an appreciation of the particle nature of electromagnetic radiation.
• Describe the phenomenon of photoelectric effect.
• Explain photoelectric effect in terms of photon energy and work function.
• Explain the function of photocell and describe its uses.
• Describe Compton's effect.
• Explain the phenomena of pair production and pair annihilation.
• Describe de-Broglie's hypothesis of wave nature of particles.
• Describe and interpret qualitatively the evidence provided by electron diffraction for the wave nature of particles.
• Understand the working principle Of electron microscope.
• Understand and describe uncertainty principle.