A bibliography is a list of works (books, articles, films, etc.) on a particular topic. Annotated bibliographies tell more about the work you are citing. An annotation can both describe and evaluate a source.An annotated bibliography includes a paragraph following each citation that summarizes the work.
A frequency polygon is a graphical display of a frequency table. The intervals are shown on the X-axis and the number of scores in each interval is represented by the height of a point located above the middle of the interval.The points are connected so that together with the X-axis they form a polygon.A frequency table and a relative frequency polygon for response times in a study on weapons and aggression are shown below. The times are in hundredths of a second.Frequency polygons are useful for comparing distributions.he intervals are shown on the X-axis and the number of scores in each interval is represented by the height of a point located above the middle of the interval. The points are connected so that together with the X-axis they form a polygon.
The utility frequency, line frequency or mains frequency is the nominal frequency of the oscillations of alternating current in an electric power grid transmitted from a power station to the end-user. In large parts of the world this is 50 Hz, although in the Americas and parts of Asia it is typically 60 Hz. Current usage by country or region is given in the list of mains power around the world. During the development of commercial electric power systems in the late 19th and early 20th centuries