Physics Exam Notes

Light Wave Interference

• Interference is noticeable with coherent and monochromatic light sources.

• Flashlights emit photons of different wavelengths and phases, making interference unobservable.

• Lasers with the same wavelength can demonstrate interference.

Nuclear Physics

• Neutron Gain:

  • Atomic number: Stays the same.

  • Neutron number: Increases.

  • Mass number: Increases.

• Mass Comparison (Before vs. After Decay):

  • Mass before decay > mass after decay + mass of emitted particles.

  • Mass difference converts to energy: E=mc^2

• Radioactive Decay Series:

  • Unstable nucleus decays into a daughter nucleus.

  • If the daughter nucleus is unstable, it decays further, creating a series of related nuclei.

Resolution and Light

• Resolution is greater with blue light due to its shorter wavelength.

• Shorter wavelength means less diffraction and better resolution.

Spy Cameras and Aperture Size

• Large apertures are advantageous for better low-light performance.

• Large openings allow more light to pass through the lens.

Coherent Light Sources

• Coherent light sources that are half a wavelength out of phase interfere destructively.

• Crest of one wave aligns with the trough of the other, canceling amplitudes and reducing light intensity.

Single-Slit Experiment

• If the wavelength of light increases, the angle to the first dark fringe increases.

• Formula: w sin θ = mλ (angle is directly proportional to the wavelength).