what are the conditions for the formation of shadow - physics - 
what are the conditions for the formation of shadow???
![](https://s3mn%20mnimgs%20com/img/shared/discuss_editlive/2191102/2012_01_06_16_34_59/high%20bird%20png)
conditions for the formations of shadows are
1 a light source, an opaque obstacle, a screen
2 umbra, that is the dark part (shown in the above figure by the
dark triangular shape) of the shadow must fall on the screen
reason: saturn has some unique characteristic like :-1. saturn has rings around it, these rings are made up of rocks, ice and dust.2. density of saturn is less than that of water (density is mass per unit volume), i.e. it is very light so if there were large enough ocean saturn would float on it. we are required to state the effect of one of the laws governing brightness. apparent brightness:b=l4πd2 where b is apparent brightness, l is intrinsic luminosity, and d is the distance from the source. [readmore]as the distance increases, the apparent brightness gets fainter as the distance from the source increases. the fainting brightness is accounted for by the spreading out of photons: as light travels away from its source, the photons get spread out over increasingly greater areas. the more the light is spread out, the fainter it appears in any given patch of area (for example, the small patch of the area covered by the opening in your eye)the correct choice is:d. far from the source, photons spread over a larger area. Regards,



From the information you have conveyed, there are complaints of small flashes or shadows of black threads and sometimes flash is a form of floaters. So that in your eyes you can see a picture of a shadow floating and moving in all directions, which in the end this condition can interfere with your vision. Some of the causes of this complaint can be caused by:



1. inflammation of the front of the eye



2. nearsightedness



3. cataracts



4. Laser action



5. Diabetes



6. inflammation of the retina



7. retinal detachment or disruption or detachment of the retinal lining



8. eye trauma



9. buildup of crystals in eye fluid



Meanwhile, the pressure of your eyeball that reaches a value of 22 mmHg, indicates the eye pressure is above normal, or is called intarocular hypertension. The normal value of eye pressure ranges from 12-21 mmHg. The condition of increased eye pressure can be caused by several conditions, such as:



1. galaucoma, or a disturbance in the circulation of fluid in the eye so that it damages the function of the optic nerve



2. drug side effects



3. diabetes



4. nearsightedness



5. eye injury



Thus, in patients with distant vision problems or patients with nearsightedness it is possible to find an increase in eye pressure and floaters.



Therefore, do regular check-ups with your ophthalmologist according to the scheduled next examination visit. The doctor will conduct periodic checks at least every 6-12 months to find out the health condition of your eyes.



What you can do is avoid eye fatigue, avoid sleeping late at night.



That's the information we can convey, read also eye pressure increases.



dr. Ulfi when a ray of light falls on a smooth and shiny surface, the whole of light is sent back in the same direction. it is called reflection. mirrors do not allow even a small amount of light to pass through them. mirrors show regular and complete reflection.when all the parallel rays reflected from a plane are not parallel, the reflection is diffused or irregular. this is not violation of law of reflection, the reason for diffused reflection is due to irregularities in the reflecting surface. A thunderstorm with lots of lighting, wind, and thunder. Photography is the process of making pictures (graph) using light (photo)...  
Light takes the most important role on produce nice pictures  
  
There`re no fixed rules about photography, it`s an art so nobody have rights to say that the photo is good or bad...  
  
During rainy day, you should prepare camera`s water-proof jacket or an umbrella to protect it against water. Some expensive cameras have been equipped with water-proof material. we’re being asked which of the following conditions occurs when a chemical change happens to a piece of wood let’s first define a physical change and a chemical change.physical change → there is a change in a matter as it goes from one physical state to another.chemical change → atoms rearrange themselves to create a new substance. now, let’s take a look at each condition:[readmore]a. is splitsplitting wood is only reducing its size. physical changeb. is paintedpainting wood is only placing paint on top of it and not really affecting the composition of the wood.  physical changec. decaysdecaying changes the integrity of the wood itself and transforms it into things like soil. chemical changed. is cutcutting wood is only reducing its size. physical changea chemical change occurs when a piece of wood c. decays. this happens because the speed of light is faster in air then that of the speed of sound. early photographers relied on the outdoor use of sunlight/daylight to expose light sensitive paper. photograms were able to be created in a darkroom, first with an oil lamp and then an electric bulb. the sun fuses hydrogen to helium in an atomic reaction similar to a hydrogen bomb, this reaction gives off energy and hence provides us with a lot radiant energy, most astronomers believe that the sun has been “turned on” for about 4.5 billion years. 

as the sun gets older, it will continue to fuse hydrogen in its core, scientists estimate that there is enough hydrogen fuel to continue this process for another 4 billion years or so, then the fun starts….

once the majority of the sun’s hydrogen is turned into helium, it stops fusing hydrogen and loses its ability to combat gravity, the sun will begin to compress under its own weight. the higher pressures and temperatures at the sun’s core will cause helium to begin to fuse into carbon in a similar process to the hydrogen fusion, this too balances out the gravity and the sun will continue to shine, but the process of fusing helium gives off more energy than the fusing of hydrogen. this additional energy streaming out of the core radiates through the “envelope”, the layers outside the core. this very high energy into the envelope heats up the envelope causing the envelope expand greatly to hundreds of times its original size. 

the part that can be seen (the envelope) is much cooler than the young sun was and it is red in color, the sun has become a red giant star. 

even though the red envelope is cooler than the young sun it is still very hot, about 5000° fahrenheit! unfortunately, for any life on planets in the inner solar system, the red giant sun's envelope will expand to engulf all the way out past earth and mars. all the oceans will be evaporated away and in fact the earth's atmosphere will be blown into space. the engulfed planets will, obivously, be uninhabitable.