Light

Chapter 8

Light

Diffraction and Interference of Light

When light passes through a slit with a size that is close to the light’s wavelength, the light will diffract, or spread out in waves. When light passes through two slits, the waves from one slit will interfere with the waves from the other. Constructive interference occurs when a wave front, or crest, from one wave coincides with a wave front from another, forming a wave with a larger crest. Destructive interference occurs when a wave front of one wave coincides with a trough of another, cancelling each other to produce a smaller wave or no wave at all.

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Constants

Period of visible light wave 2 x 10^-15

Speed of light c≈3 x 10⁸ m/s

Refraction of light sin ө 2/sin ө1 = V₂/V₁ = constant

Diamond refraction λ⁰ = 589nm 2.419

Infused quartz refraction V= 0/n = 3.00 x 10 ⁸ m/s/1.458

Deep violet .000039 cm

Dark red .000076 cm

Blue .00005 cm

Green .000055 cm

Red ↓ (.003 cm to 25 km) heat/radio

x-ray – ultraviolet’s - .00000004 cm

gamma – ultraviolet’s – one ten-millionth of violet

Braggs reflection is ΔK=-G geometry conditions for nλ=2d_nki sin ө, n=order of diffraction.

Equitant wave lengths corresponding to the root = mean- sq, velocities of a neutron gas at 0⁰c and 100⁰c are 1.55Å and 1.33Å respectively.

Particle/Wave

In 1924 deBroglies hypothesis states the light exhibits both wave like and particle like properties P=h/λ the moving particles P=mu would have an associated wavelength λ given by λ=h/p = h/mu. Electrons, protons, neutrons and simple atoms and molecules all agree with deBroglie formula. Light and matter have dual natures. This schizophrenic behavior of matter and radiation shows that neither the particle model nor the wave model is strictly correct. They are not mutually exclusive but rather they are complementary description. This means that we can not know the instantaneous values of both the position and the momentum to an arbitrary degree of accuracy.

friction

If a continuous spectrum of light is subjected to repeated reflection from an ionic crystal the light eventually becomes a narrow band of frequencies. Reflected light is known as “residual rays.”

Three unexplained effects of photoelectric; Kinetic energy of the ejected electrons is independent of the intensity of the light. Electrons are only ejected if the frequency of light exceeds a certain threshold. The kinetic energy of the ejected electron is proportional to the frequency of the incident light. Maxwell equations made the physical prediction that “light travels with the same speed, in all directions. A spherical pulse of light will appear spherical. Galileo’s the speed of an object is a private relative concept. If the speed of light is infinite there is no conflict between Galileo’s space-time and Maxwell’s laws of electromagnetism and optics.

Cerenkov radiation states that electromagnetic radiation, usually bluish light, emitted by a beam of high energy charged particles at a speed greater than light. The effect is similar to that of a sonic boom causing a shock wave set up in the electromagnetic field.

A rainbow can be seen as a natural example of refraction, a bending of light, reflection is light bounced off mirrors. Light is a particle and a wave. All waves have crests, troughs, wave length, amplitude, and frequency. A wave length is the distance between crests. Frequency is the number of waves in a fixed time and point. Amplitude is the distance between crest and trough.

Young, Thomas made the comparison between sound waves produced by a tuning fork and waves of light. Young used the modulus of elasticity-stress applied to a body to the strain produced. The bulk modulus is the ratio of the pressure on a body to its fractional decreases in volume. The shear (or rigidity) is the tangential force per unit area divided by the angular deformation in radians. Young interference is the interaction of two or more wave motions affecting the same part of a medium so that the instantaneous disturbances in the resultant waves are the vector sum of the instantaneous disturbances in the interfering is when to waves coincide.

Destructive interference is the maxima of one wave hitting the minima of another wave.

Lasers produce coherent radiation and produce interference effects like holography and measuring. Superluminal (faster than light) tachyons are the link between Polari ability and refractive Lorentz transformation, α=(3/4 π n)[ (N ² -1/n ² +2)] x ¹ =β (x- V ^t ), Y ¹ =y  z ¹ =z  t ¹  = β (τ –vx/c ² ) transforming the position and motion parameters.

Lasers are electromagnetic force traveling as a wave and electromagnetic waves that have two components, an electric field, and a magnetic field that vibrate at right angles to one another. Electromagnetic energy of the proper wave length can excite the electrons until one or more of them leave the atom altogether, called an ion, positively charged. The key is not the wattage but wavelength. Lasers produce light that is precisely spaced and lined up. The quality of laser light is called coherent. Stimulated emission is an atom already in an excited state and it is struck by another photon, the electron will drop back to a lower energy orbit and give off a photon. Moreover the incoming photon will not be absorbed at all. So there will be two photons leaving the atom. A resonator cavity reflects electromagnetic waves back and forth (usually a box) getting atoms or molecules into the excited state and then holding them there, is called population inversion. The Meta stable state of the atom is only partly stable; in this state a few photons will be emitted. The photon strikes other atoms producing stimulated emissions. The more tightly bunched its waves are the more information can be carried. Light can exert a minuscule amount of pressure. The light pressure is determined by hv=mc², when a bean of circularly polarized light is perfectly reflecting then the pressure is twice the value, P=1/c namely 21/c. This is because a photon on being reflected back, undergoes a change of momentum of P-(-P) = 2P. Each photon transfers twice as much momentum to the surface; this momentum causes torque on the surface. The magnitude of the torque per unit area is J=1/2πv = 1/w or T=Nh/2π. This implies that the photons carry angular momentum as well as linear momentum. A total internal reflection is mirror surfaces “spherical” reflecting the light to the interior. Lasers can be classified either by the material that is used to produce laser action or by the method used to excite the active atoms. The material can be solid, liquid, or gas. The method of exciting the material can be optical “light” electrical or chemical. The differential equations completely replace the Newtonian theory of motion, provided the masses are represented as singularities of the field. They contain the laws of force and motion while eliminating inertial systems. The fact that masses appear as singularities indicates that these masses can not be explained by symmetrical fields or gravitational fields. Not even the fact that only positive gravitating masses exist can be deduced. Gravity has 10 differential equations. The principle of general relativity implies the number of functions to be determined by the differential equations is 10-4=6. Six differential equations that is independent of one another. The remaining four equations are relations (identities). The most natural theoretical system must replace symmetrical tensor fields with non-symmetrical tensors bring the differential equations up to 16 independent components, which still doesn’t satisfy all the laws and parameters of gravity. Everything is a particle and a field at the same time, and you can not give one up or the other, but still we do not know how to combine them as one equation.

Light Quanta/ Thermal Radiation

Electromagnetic energy that is emitted from a surface is called thermal radiation. Radiation consists of a continuous spectrum of frequencies extended over a wide range. The spectral distribution and the amount of energy radiated depend on the temperature of the emitted surface. The spectral distribution has a definite frequency (or wave length) at which the radiation power is maximized and varies in direct proportion to the absolute temperature. This is known as Wien’s law. At 500^o C and above, the body glows visibly. Measurements indicate that the total power increases s the forth power of the absolute temperature, known as Stefan-Boltzmann law. In a hollow cavity inside a single body thermally insulated from the cavity walls. If the cavity walls are maintained at a constant temperature, the radiation then fills the cavity and some of it is absorbed by the body. The body also emits radiation and equilibrium is attained when the body emits at the same rate that it absorbs. Irradiance of the radiation within the cavity;  I is the total power per unit area incident on the body, b is the fraction of incident power that the body absorbs and H is the radiance or power per unit area that it emits for equilibrium H=bI. In the case of several bodies within a cavity the equilibrium of each body is I=H₁/b₁=H₂/b_{2 =} ... at a given temperature the ratio of the emitted power to the fraction of power absorbed is the same for all bodies and is equal to the irradiance within the cavity, known as Kirchhoff’s law.  The perfect absorber is called blackbody, b=1 and the corresponding value of H is the maximum possible H_max = 1  this is also known as Hohlraumstralung.

Photon

One photon can start an avalanche of 10,000 or more reactions. Light causes changes in matter and matter causes changes in light. Light waves can be used as a finger print for all materials. Ultra violet light causes movement of electrons from orbital to orbital. Microwave radiation can stimulate rotational motion. Infrared light stimulates vibrations, dipoles caused by vibrations, then there is no field to which oscillating electromagnetic field can interact. All living things are physico-chemical machines.

Physiology is the physical and chemical processes in the body. Hemoglobin is made up of several thousand atoms, a 3 dimensional subjected to intermolecular force. Many biochemical systems, heart, lungs, endocrine systems are non-linear oscillating systems.

Fechner’s Law – the more you have the more it takes to notice a difference. Fenchners oscillating reaction is a heterogeneous system, it takes place in two phases, solid-phase, and electrode and liquid phase solution.

Oscillations is glycolyis, it is the reaction in the body in which sugar is broken down for energy. Belousov-Zhabolinsky  or BZ reactions is a reaction solution, periodically cycles between rich red, deep blue and new leaf green in a series of sudden and dramatic colors. When applied to the oscillations of glycolyis form pulses of color. The nature of the human cell is an impressive, entropy-defying, energy-utilizing, self-assembling, self repairing, environment responding nanobot. Nanotubes pound per pound are stronger than steel and pound per volume are 1/6 the weight.   

Non-linear interaction between light and matter allows the frequency of light to be doubled or tripled.

Sound and light are mutually helpful, the conceptions being explained and strengthened and defined by the other. Pitch is dependent of wave length, which answers to the color of light. The range of the visible spectrum is about an octave.

 The transference of a wave from one tuning fork to another, it is the motion of each wave hitting the other tuning fork. These impulses are added to themselves, wave after wave. In 5 seconds that equal to 1,280 waves hitting the other tuning fork. This is called The influence of synchronism.