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.
Different Graduate Degrees. According to the U.S. Bureau of Labor Statistics (BLS), the highest graduate-level degrees in psychology are a Ph.D. in Psychology and a Doctor of Psychology (Psy.D). A Ph.D. in Psychology is a research-intensive graduate program. Most Ph.D. programs last about four to six years. The first few semesters in a Ph.D. program are filled with seminar and research classes. Those classes help a graduate student learn the general field of psychology in small classrooms where communication with fellow students and a professor is crucial.