Apply Bernoulli's theorm at the two points of fluid flow.

A laser (acronym for Light Amplification by Stimulated Emission of Radiation) is an optical source that emits photons in a coherent beam.

 

Laser light is typically near-monochromatic, i.e., consisting of a very small band of wavelengths or a very specific color, and emitted in a narrow beam. This contrasts with common light sources, such as the incandescent light bulb, which emit incoherent photons in almost all directions, usually over a wide spectrum of wavelengths.

 

A laser is composed of an active laser medium, or gain medium, and a resonant optical cavity. The gain medium transfers external energy into the laser beam. It is a material of controlled purity, size, concentration, and shape, which amplifies the beam by the quantum mechanical process of stimulated emission, discovered by Albert Einstein while researching the photoelectric effect. The gain medium is energized, or pumped, by an external energy source. Examples of pump sources include electricity and light, for example from a flash lamp or from another laser. The pump energy is absorbed by the laser medium, placing some of its particles into high-energy ("excited") quantum states. When the number of particles in one excited state exceeds the number of particles in some lower-energy state, population inversion is achieved. In this condition, an optical beam passing through the medium produces more stimulated emission than the stimulated absorption, so the beam is amplified. An excited laser medium can also function as an optical amplifier.

 

 

The light generated by stimulated emission is very similar to the input signal in terms of wavelength, phase, and polarization. This gives laser light its characteristic coherence, and allows it to maintain the uniform polarization and monochromaticity established by the optical cavity design.

 

 

MASERS - MICROWAVE AMPLIFICATION BY STIMULATED EMISSION OF RADIATION

 

LASERS- LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION

 

NORMAL POPULATION- WHEN IN THE LASING MEDIA (LIKE YAG - YTTRIUM ALUMINUM GARNET, ALUMINUIUM OXIDE IN RUBY) THE GROUND STATES ARE FILLED AND METASTABLE STATES ARE LESS OR UNPOPULATED.

 

POPULATION INVERSION- HERE THE NUMBER OF ELECTRONS IN METASTABEL STATES ARE VERY LARGE IN COMPARISON TO THE GROUND STATE WHICH ON STIMULATED EMISSION GIVES PHOTON OF THE SAME FREQUENCY AS THAT OF STIMULATED PHOTON, THUS THE STIMULATED AND EMITTED PHOTON ARE COHERENT AND THIS IS RESPONSIBLE FOR LASING ACTION

 

HOLOGRAPHY - IS THE PROCESS IN WHICH WE USE LASERS, GENERATE THE INFORMATION LIKE COHERENCY, PHASE ETC. TO OBTAIN 3-D PICTURE OF THE IMAGE.

In pear shaped charged body the distribution of charges is obviously not uniform unlike in a spherical body

 

 

 

In electricity, a corona discharge is an electrical discharge brought on by the ionization of a fluid surrounding a conductor, which occurs when the potential gradient exceeds a certain value, but conditions are insufficient to cause complete electrical breakdown or arcing.

 

 

 

 

Thus above phenomenon is due to polarisation of charges. Something more on it is given below

 

If a material contains polar molecules, they will generally be in random orientations when no electric field is applied. An applied electric field will polarize the material by orienting the dipole moments of polar molecules. This decreases the effective electric field between the plates and will increase the capacitance of the parallel plate structure. The dielectric must be a good electric insulator so as to minimize any DC leakage current through a capacitor.

If a matter is present between the two charges then it net force between th two charges. This is because of some permittivity of the meduim or matter.

 

Say its relative permittivity is , then force betwen the two charges is altered as

 

F' = F/ 

 

Where F =  q₁q₂/4₀ = force between the the charges in the absence of matter

 

And F' = force between the charges in the prescence of matter.

 

The physical explantion of this phenomenon is easy.

As when the matter say dielectric is introduced between teh point charges then depending on the condition whether the dielectric material is

a) Polar material or

 

b) Non-polar material.

 

The rescence of elctric field between the two charges tends to polarise the dielectric or it aligns the microscopic dipole moments in the direction of external electric field. Thus generating internal electric field resulting into the altering of force between the point charges.

Problem) What will b the value of g if bob of simple pendulum is made to oscillate in some fluid of density d?

 

Solution) If density of bob material is = d₁

 

Also if volume of the bob = V

 

Density of fluid in which simple pendulum is oscillating = d₂

 

Then the buoyancy force due to fluid on the bob = F_b =  V d₂g (against gravity)

 

So, Resultant Force on the bob is given by = Gravitaional force - Buoyancy force

 

Or Resultant force on the bob = V d₁ g - V d₂g

 

If effective acceleration due to gravity = g' then above equation can be written as

 

V d₁g' = V d₁ g - V d₂g

 

or, g' = (d₁  - d₂) g / d₁

 

In your case if the spring constant = k

 

Then on dividing the spring in two equal parts will increase the spring constant by a factor of 2

 

So spring constants of two equal halves is = 2k

 

So on parallel combination of these two springs the effective spring constant is

 

k_parallel = 2k + 2k = 4k

Two springs of spring constants k₁ & k₂ are combined in parallel then effective total spring constant is

 

k(parallel) = k₁ + k₂.

 

But if the two springs of are combined in series then effective sping constant is given by

 

 

One might say that the spring constants will add like a capacitor network, not like a resistor network.  That is, the spring constants of a series network are summed as the inverse.  The spring constants of a parallel network are summed directly.