ATP in Energy Coupling and Transfer

• ATP is the primary energy currency of cells.
• Electromagnetic waves are formed when an electric field comes in contact with a magnetic field which are perpendicular (at right angles) to each other. They are also perpendicular to the direction of the EM wave.
• Wavelength


  The distance between wave crests or troughs, measured in micrometers or microns (μm)
• Energy


  Electromagnetic waves bring energy into a system by virtue of their electric and magnetic fields. The amount of energy in the wave increases as wavelengths get smaller and tighter.
• Frequency


  The number of sinusoidal cycles (oscillations or complete wavelengths) that pass a given point per second, measured in Hertz (Hz) or cycles per second (cps)
• Frequency is proportional to the reciprocal of the wavelength. Thus, longer wavelengths correspond to lower frequency radiation and shorter wavelengths correspond to higher frequency radiation. The quantity of frequency remains the same when light passes from one medium to another.
• Speed


  Electromagnetic waves at different wavelengths and frequencies all travel at the same speed, the speed of light, which is equivalent to 3 x 10-8 m/s (186,000 mi / s)
• Relationship between wavelength, frequency, and speed of light


  c = λf, where c is the speed of light, f is the frequency, and λ is the wavelength
• Optical Density


  When light travels from one medium to another, it slows down and changes direction (refraction). This is because the speed and wavelength of light changes when it enters new medium, but its frequency remains constant.
• Physical Density


  The mass/volume ratio of a material
• Optical Density


  The tendency of the atoms of a material to maintain the absorbed energy of an electromagnetic wave in the form of vibrating electrons before reemitting it as a new electromagnetic disturbance. The more optically dense that a material is, the slower that a wave will move through the material.
• Index of Refraction


  The ratio of the phase velocity of a wave phenomenon such as light or sound in a reference medium to the velocity in the medium itself. When the amount of bending is bigger, the difference in n is bigger for the two materials.
• Formula to calculate index of refraction

  n = c/v, where n is the index of refraction, c is the speed of light, and v is the speed of light in the material
• Solving for index of refraction

  1. Given: v = 2.76 x 10^8 m/s, Find: n

  2. n = c/v = 3 x 10^8 m/s / 2.76 x 10^8 m/s = 1.09
• Relationship between refractive index, permittivity, and permeability


  n = sqrt(εr * μr), where εr is the permittivity of the material and μr is the permeability of the material
• Index of refraction


  The ratio of the phase velocity of a wave phenomenon such as light or sound in a reference medium to the velocity in the medium itself
• When the amount of bending is bigger, the difference in index of refraction is bigger for the two materials
• Index of refraction of various materials


  • See Figure 2
• Formula to calculate index of refraction


  n = c/v
• Speed of light in an unknown medium is 2.76 x 10^8 m/s, what is the index of refraction?
• Refractive index can be determined through permittivity and permeability


  n = sqrt(εr * μr)
• Comparison between permittivity and permeability

  • Permittivity: Measures resistance to electric field formation
  • Permeability: Measures ability to allow magnetic lines of force to pass through
• Permittivity of free space is 8.85 F/m, permeability of free space is 1.26 H/m
• Dispersion of light


  When light passes through a prism, light waves of different frequencies bend on varying amounts, separating the white light into different colors
• The dispersive property of the prism could be further explained by a law called Snell's Law
• Snell's Law

  The law of refraction discovered by Willebrord Snell in 1621, which gives the degree of refraction and relationship between the angle of incidence, the angle of refraction and refractive indices of a given pair of media
• Snell's Law


  1. n1sin(q1)= n2sin(q2)

  2. where n1 = index of refraction of the first medium, n2 = index of refraction of the second medium, q1 = angle of incidence, q2 = angle of refraction
• When light enters a denser substance or with higher refractive index, it bends more towards the normal line. But when it enters a less dense material, it bends away from the normal line
• Refractive index


  • Determines how much the speed of light is reduced when passing through a medium
• The index of refraction of air is less than the index of refraction of water
• When light passes from air to glass, its speed is reduced
• When light passes from air to water, its speed is reduced and it bends towards the normal
• When light passes from air to a less dense medium, it bends away from the normal
• Solving Snell's Law problems

  1. Given: q1, n1, n2

  2. Find: q2

  3. Use formula: n1sin(q1) = n2sin(q2)

  4. Solve for q2
• Snell's Law can be applied in cameras, contact lenses, eyeglasses, but not in mirrors
• Snell's Law is the other term for the law of refraction
• Willebrord Snell discovered the law of refraction, also known as Snell's Law
• The quantities involved in Snell's Law formula are index of refraction, angle of incidence, and angle of refraction. Wavelength is not a quantity in the formula
• The formula for Snell's Law is n1sin(q1) = n2sin(q2)
• Development


  Involves the formation of sex cells, zygote formation, subsequent stages in one's life span. Development is terminated by death.