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Saturday, February 20, 2016

Why Is the Sun Yellow?

If you ask a random person to tell you what color the sun is, chances are he will look at you like you're an idiot and tell you the sun is yellow. Would you be surprised to learn the sun is not yellow? It's actually white. If you were to view the sun from the International Space Station or the moon, you'd see its true color. Check space photos online. See the true color of the sun? The reason the sun appears yellow during the day from Earth, or orange to red at sunrise and sunset, is because we view our favorite star through the filter of the atmosphere.

The True Color of the Sun

If you view sunlight through a prism, you can see the entire range ofwavelengths of light. Another example of the visible portion of the solar spectrum is seen in the rainbow. Sunlight isn't a single color of light, but a combination of the emission spectra of all the elements in the star. All of the wavelengths combine to form white light, which is the net color of the sun. The sun emits different amounts of various wavelengths. If you measure them, the peak output in the visible range is actually in the green portion of the spectrum (not yellow).
However, visible light isn't the only radiation emitted by the sun.
There's also blackbody radiation. The average of the solar spectrum is a color, which indicates the temperature of the sun and other stars. Our sun averages about 5800 Kelvin, which appears nearly white. Rigel appears blue and has a temperature exceeding 100000K, while Betelguese has a cooler temperature of 3500K and appears red.

Friday, February 19, 2016


SSC Chemistry


See Why the Sky Is Blue and Sunset Is Red - Easy Experiment

The sky is blue on a sunny day, yet red or orange at sunrise and sunset. The different colors are caused by scattering of light in the Earth's atmosphere. Here is a simple experiment you can do to see how this works:

Blue Sky - Red Sunset Materials

  • water
  • milk
  • transparent container with flat parallel sides
  • flashlight
A small rectangular aquarium works well for this experiment. Try a 2-1/2-gallon or 5-gallon tank.
Any other square or rectangular clear glass or plastic container will work.

Conduct the Experiment

  1. Fill the container about 3/4 full of water. Turn on the flashlight and hold it flat against the side of the container. You probably won't be able to see the beam of the flashlight, although you may see bright sparkles where the light strikes dust, air bubbles, or other small particles in the water. This is much like how sunlight travels through space.
  2. Add about 1/4 cup of milk (for a 2-1/2 gallon container -- increase the amount of milk for a larger container). Stir the milk into the container to mix it with water. Now, if you shine the flashlight against the side of the tank, you can see the beam of light in the water. Particles from the milk are scattering light. Examine the container from all sides. Notice if you look at the container from the side, the flashlight beam looks slightly blue, while the end of the flashlight appears slightly yellow.
Heterogeneous and homogeneous refer to mixtures of materials in chemistry. The difference between heterogeneous and homogeneousmixtures is the degree at which the materials are mixed together and the uniformity of their composition.

homogeneous mixture is a mixture where the components that make up the mixture are uniformly distributed throughout the mixture. The composition of the mixture is the same throughout.
There is only one phase of matter
 observed in a homogeneous mixture
You know if you put fresh cut flowers in water it will help keep them from wilting. If you have a packet of cut flower preservative from a florist or the store, it will helpthe flowers to stay fresh much longer. You can make cut flower preservative youself, however. There are several good recipes, made using common household ingredients.

Keys to Keeping Cut Flowers Fresh

  • Give them water.
  • Give them food.
  • Protect them from decay or infection.
  • Keep them cool and out of direct sunlight.
The floral preservative provides flowers with water and food and contains a disinfectant to prevent bacteria from growing. Making sure your vase is clean will also help. Discard any decaying leaves or flowers, because the freshness of flowers is influenced by the gases and bacteria found on wilted or rotting plant material. Also, don't set your flowers near ripe fruit, because the chemicals from the fruit (such as ethylene) will 'ripen' your flowers. If you can, keep your flowers in a cool location and out of sun. Minimize air circulation, since it speeds evaporation and can dehydrate your flowers.

Medicinal chemistry

Medicinal chemistry is a stimulating field as it links many scientific disciplines and allows for collaboration with other scientists in researching and developing new drugs.Medicinal chemists apply their chemistrytraining to the process of synthesizing new pharmaceuticals.

নেপালের প্রধানমন্ত্রী খাদগা প্রসাদ শর্মাকে ফোন দিয়েছেন প্রধানমন্ত্রী শেখ হাসিনা

নেপালে বিমান বিধ্বস্ত হওয়ার ঘটনায় দেশটির প্রধানমন্ত্রী খাদগা প্রসাদ শর্মাকে ফোন দিয়েছেন প্রধানমন্ত্রী শেখ হাসিনা। নেপালের প্রধানমন্ত্রী গ...

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