Week 4 Content Questions

Light is one form of electromagnetic radiation . What are electromagnetic waves , and what other types exist besides light ? Compare their wavelengths

Electromagnetic waves are disturbances caused by the oscillation of charged particles . It consists of two parts , an electric field and a magnetic field oscillating perpendicular to each other . The wave is self-sustaining , and propagates at a direction perpendicular to both the electric field and magnetic field

There is a whole spectrum of electromagnetic waves . The ones with the longest wavelengths (range : 1 cm-1km ) are the radio waves . After the

radio waves , microwaves have the next longest wavelength (range 1mm-10cm . Then , we have the infrared waves (range : 1 ?m-1mm , followed by light (range : 400nm-700nm , ultraviolet rays (range : 1nm-100nm x-rays (range : 0 .1nm-10nm , and gamma rays , which have the shortest wavelengths amongst the different electromagnetic radiations (range 0 .01nm-0 .1nm

b . How you determine the temperature , composition , and motion of an object from its light spectrum

Different elements emit and absorb light waves differently . Hence , when viewed through a spectroscope , different elements will have different spectral patterns . The object 's composition is obtained from noting which spectral lines are present or absent . We can also determine the density of the object depending on the amount of lines present in the spectrum . The more lines and the more continuous the spectrum , the denser is the material

On the other hand , the temperature of the object will affect the shapes spectral lines emitted by the object . If objects have high temperatures their spectral lines will be broader , that is , it is spread over more frequencies than if it had lower temperature . To determine temperature

Finally , the Doppler Shift tells us the motion of the object , whether it is moving away or toward us , and with what speed . When the observed object is moving toward us , the spectral lines we observe occur at shorter wavelengths when we compare it to those measured in the laboratory . This is called blueshifted ' On the other hand , if the object is moving away from us we observe the lines to occur at longer wavelengths . In this case we say that the lines are redshifted ' The amount of shifting will determine the speed of motion

In what way do astronomers infer that the Sun 's energy comes from nuclear fusion reactions ? How do we know it does not come from chemical burning

Even though both nuclear fusions and chemical reactions result in the release of energy , nuclear fusions release much more energy than chemical reactions . This is due to the nature of each reaction . Given that the energy that the sun produces is extremely high , it is impossible that chemical reactions are fuelling it , for if that were the case , then the sun will not be producing enough energy to sustain life on Earth . If it were chemical reactions powering it , it would be producing roughly one-millionth of the energy it is producing now

Explain how the Sun produces energy by nuclear fusion

Because of the amount of matter...