This list includes different tools to help you locate information in physics.
There is one encyclopedia source: AccessScience
There are journal article databases to look for Physics and Materials Science research information:
INSPEC, Web of Science, and arXiv.org
There are two tools to search for journal article citations:
Web of Science and Google Scholar
There are lots of physics classroom lectures, problem sets and exams on the web:
Khan Academy has many introductory lecture videos. Note that problem set solutions may be locked.
CrashCourse has videos on Physics course topics.
MIT OpenCourseWare has lectures, problem sets and exams online.
UCI Open has lectures, problems and solutions in individual lectures.