Thus by 1803 there were two known rare earth elements, yttrium and cerium, although it took another 30 years for researchers to determine that other elements were contained in the two ores ceria and yttria (the similarity of the rare earth metals' chemical properties made their separation difficult).
For instance, students who pursue a Ph.D. in psychology usually take from five to seven years depending upon required coursework as well as internship and supervised residency requirements.
To earn your Ph.D. in psychology, you will need 5-7 years to earn the degree. You will need to finish all of the required classes and you also will have to do an internship or residency of some sort. A Ph.D.program usually ends with a detailed and long dissertation.This paper tends to be 200-300 pages in length and can take you a year or more to complete. The lengthy dissertation is a major reason why earning your Ph.D. takes so long. To earn your Psy.D. degree, you need 4-6 years to finish the degree.ou will need to finish all of the required classes and you also will have to do an internship or residency of some sort. A Ph.D. program usually ends with a detailed and long dissertation. This paper tends to be 200-300 pages in length and can take you a year or more to complete.