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.
Earn Your Doctorate Degree (Timeline: 4 to 7 Years) The length of your doctoral program depends on many factors including the specialty area you are pursuing as well as whether or not you already earned a masterâs degree. In order to become a licensed psychologist, you will need to earn either a Ph.D. or a Psy.D.