Answer:
38
Explanation:
Symbol: Sr
Atomic mass: 87.62 u
Electrons per shell: 2,8,18,8,2
Atomic number: 38
Electron configuration: [Kr] 5s2
Van der Waals radius: 255 pm
Valence electrons: two
Answer:
ptic fiber communication and satellite communication are the leading technologies which are revolutionizing the world of telecommunications. Both technologies have their advantages and limitations which make them suitable for certain type of applications. This article will provide an overview of optic fiber and satellite communication technologies and present a comparison of the features and related issues.
Optic Fiber Communication
Optic Fiber communication transmits information by sending pulses of light (using laser) through an optic fiber. The low signal loss in optic fibers and high data rate of transmission systems, allow signals with high data rates (exceeding several Gbps) to travel over long distances (more than 100 km) without a need of repeater or amplifier. Moreover, using wavelength division multiplexing (WDM) allows a single fiber to carry multiple signals (upto 10 different signals) of multi-Gbps transmissions. Optic Fiber communication offers extremely high bandwidth, immunity to electromagnetic interference, non-existent delays and immunity from interception by external means. In the 1980s and 1990s, the continents were linked together using undersea optic fiber bringing about a paradigm shift in the global telecommunications.
These advancements in optic fiber communication has resulted in decrease of satellite communications for several types of communications. For instance, transmission between fixed locations or point-to-point communications, where large bandwidths are required (such as transoceanic telephone systems) are made through optic fiber instead of using satellite communication. Optic Fiber communication is also used to transmit telephone signals, Internet communication, LAN (Gigabit LAN) and cable television signals.
Satellite Communication
Satellite communications use artificial satellites as relays between a transmitter and a receiver at different locations on Earth. Satellite systems allow users to bypass typical carrier offices and to broadcast information to multiple locations. Communications satellites are used for radio, TV, telephone, Internet, military and other applications. There are more than 2,000 satellites around Earth’s orbit, being used for communication by both government and private organizations.
Communication Satellites are LOS (line-of-sight) microwave systems with a repeater. These satellites rotate around the earth with the speed of earth and are known as geostationary satellites. The limitations of antenna size also limits focusing capability making the coverage for a single satellite transmitter very large. This makes satellite communication ideal for TV and radio services as the signal has to flow from a single point to many points in a single direction. The large distance of satellites from the earth (about 22,300 miles) results in delays which adversely effects two-way communication like mobile conversations. Low earth orbit satellites can be used for two-way mobile communication because less power is required to reach those satellites.
Explanation:
2.) Average atomic mass =Σ (abundance x molar mass) /100
= (12.64 x 302.04 + 18.23 x 304.12 + 69.13 x 305.03) /100
=304.486 u(Dalton) . This is avg atomic mass.
<u>Answer:</u> The energy of one photon of the given light is 
<u>Explanation:</u>
To calculate the energy of one photon, we use Planck's equation, which is:
where,
= wavelength of light = 
(Conversion factor: 
)
h = Planck's constant = 
c = speed of light = 
Putting values in above equation, we get:
Hence, the energy of one photon of the given light is
There are many safety precautions and rules you MUST follow during labs.
for this incident here is what you should do:
1)Notify your Instructor and partner
2) if the liquid is toxic (like not water or vinegar) then let your Instructor handle it properly, or follow your instructors orders (like if they say to put a towel over it or something like that)
3) Broken glassware, minus mercury thermometer, must be immediately cleaned up, do not use your bare hand, always wear gloves.
4)dispose of the broken glass properly and clean the liquid up (unless it is harmful, then let your instructor do it)
