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Physics Units and Constants

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  • What is the SI unit of electric charge and its equivalent unit?
    The SI unit is the Coulomb (C), equivalent to \(1\text{ A} \cdot \text{s}\).
  • Define electric potential and its unit.
    Electric potential is measured in Volts (V), equivalent to \(1\text{ J/C}\).
  • What is capacitance and its unit equivalence?
    Capacitance is measured in Farads (F), equivalent to \(1\text{ C/V}\).
  • What is the unit of electric current and its equivalent?
    Electric current is measured in Amperes (A), equivalent to \(1\text{ C/s}\).
  • Define resistance and its unit equivalence.
    Resistance is measured in Ohms (Ω), equivalent to \(1\text{ V/A}\).
  • What is the unit of magnetic field and its equivalent?
    Magnetic field is measured in Tesla (T), equivalent to \(1\text{ N} \cdot \text{s} / (\text{C} \cdot \text{m})\).
  • Define magnetic flux and its unit equivalence.
    Magnetic flux is measured in Webers (Wb), equivalent to \(1\text{ T} \cdot \text{m}^2\).
  • What is inductance and its unit equivalence?
    Inductance is measured in Henrys (H), equivalent to \(1\text{ V} \cdot \text{s/A}\).
  • What is the typical unit for wavelength in optics?
    Wavelength (λ) is typically measured in nanometers (nm) or meters (m). Note: \(1\text{ nm} = 10^{-9}\text{ m}\).
  • What is the unit of frequency and its equivalence?
    Frequency (f) is measured in Hertz (Hz), equivalent to \(1/\text{s}\) or \(\text{s}^{-1}\).
  • Define the index of refraction and its unit.
    The index of refraction (n) is dimensionless and defined as the ratio of speeds: \(n = c/v\).
  • What is optical power and its unit equivalence?
    Optical power (P) is measured in Diopters (D), equivalent to \(1/\text{m}\).
  • What is the SI unit of temperature in thermodynamics?
    Temperature (T) is measured in Kelvin (K). Always use Kelvin for gas law calculations.
  • What is the unit of heat or energy and its equivalence?
    Heat or energy (Q or U) is measured in Joules (J), equivalent to \(1\text{ kg} \cdot \text{m}^2/\text{s}^2\) or \(1\text{ N} \cdot \text{m}\).
  • What is entropy and its unit?
    Entropy (S) is measured in Joules per Kelvin (J/K).
  • Define specific heat and its unit.
    Specific heat (c) is measured in Joules per kilogram Kelvin, or \(\text{J}/(\text{kg} \cdot \text{K})\).
  • What is the permittivity of free space and its value?
    Permittivity of free space (ε₀) is \(8.85 \times 10^{-12} \text{ C}^2/(\text{N} \cdot \text{m}^2)\).
  • What is the permeability of free space and its value?
    Permeability of free space (μ₀) is \(4\pi \times 10^{-7} \text{ T} \cdot \text{m/A}\).
  • What is the approximate speed of light in vacuum?
    The speed of light (c) is approximately \(3.00 \times 10^8 \text{ m/s}\).