Illegal immigration is making headlines, as the American society is struggling to determine the economic and ethical appropriateness of a border wall with Mexico. The purpose of this paper is to review the problem of illegal migration from an economic, mostly macroeco- nomic, standpoint. The severe tensions facing the government justify the relevance of the topic. The paper begins with an insight into the history of immigration in America. The relationship between the eco- nomics and politics of immigration is discussed. The paper includes statistics to evaluate the key attributes of the immigrant labor force in the U.S. The role of illegal immigrants in the economy is thoroughly analyzed. The impacts of migrant workers on the country’s GDP are also estimated. Arguments are included to evaluate the welfare burden created by working illegal immigrants in the U.S. The paper raises questions of legalization for immigrant workers without legal status. Recommendations and implications for future research are included.
\noindent It was required to measure the focal lenghts of different lenses that are in the optics laboratory, each one of this lenses have a thoerical focal lenght provided by the fabricant; to measure and check these lenghts an experimental arrangement was placed with a rail mounted to place the lenses, a laser and a screen. The focal lenghts were measured and checked succesfully, leading us to the image formation of each lens using the same arrangement, but instead of the laser, an halogen ligh source was used. The different images and magnifications were obtained due to different distances of the lamp placement.