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Physics: Electromagnetism and Optics Concepts

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  • What is the index of refraction?
    The index of refraction is the ratio of the speed of light in a vacuum to its speed in a given medium.
  • State Snell's law of refraction.
    Snell's law relates the angles of incidence and refraction: \(n_1 \sin \theta_1 = n_2 \sin \theta_2\).
  • What causes refraction of light?
    Refraction occurs because light changes speed when passing between media with different indices of refraction.
  • Define inductance.
    Inductance is the property of a conductor by which a change in current induces an electromotive force (emf) in itself or nearby conductors.
  • What is self-inductance?
    Self-inductance is the induction of emf in a circuit due to a change in its own current.
  • How is energy stored in an inductor?
    Energy is stored in the magnetic field of an inductor and is given by \(U = \frac{1}{2} L I^2\).
  • What are electromagnetic waves?
    Electromagnetic waves are oscillating electric and magnetic fields that propagate through space carrying energy.
  • How are electromagnetic waves generated?
    They are generated by accelerating charges, such as oscillating electrons in antennas.
  • Describe the propagation of electromagnetic waves.
    EM waves propagate at the speed of light with electric and magnetic fields perpendicular to each other and the direction of travel.
  • What is the electromagnetic spectrum?
    The electromagnetic spectrum is the range of all EM wave frequencies, from radio waves to gamma rays.
  • Explain the Doppler effect for electromagnetic waves.
    The Doppler effect is the change in frequency or wavelength of EM waves due to relative motion between source and observer.
  • How is the energy of an electromagnetic wave related to its intensity?
    The energy carried by an EM wave is proportional to its intensity, which is the power per unit area.
  • What is polarization of electromagnetic waves?
    Polarization is the orientation of the electric field vector in an EM wave.
  • How can light be polarized?
    Light can be polarized by reflection, scattering, or passing through polarizing filters.
  • What is the relationship between frequency and wavelength in EM waves?
    Frequency and wavelength are inversely related by \(c = \lambda f\), where c is the speed of light.
  • What happens to light speed when it enters a medium with higher index of refraction?
    Light slows down when entering a medium with a higher index of refraction.
  • What is the formula for the induced emf in a coil due to self-inductance?
    Induced emf is \(\mathcal{E} = -L \frac{dI}{dt}\).
  • What determines the intensity of an electromagnetic wave?
    Intensity depends on the amplitude of the electric and magnetic fields and is proportional to the square of the amplitude.
  • What is the significance of the magnetic field in an electromagnetic wave?
    The magnetic field is perpendicular to the electric field and direction of wave propagation, enabling energy transfer.
  • How does the Doppler effect affect the observed frequency of light from a moving source?
    If the source moves toward the observer, frequency increases (blue shift); if away, frequency decreases (red shift).