What is an example of a primary source in history?
Primary sources may include diaries, letters, interviews, oral histories, photographs, newspaper articles, government documents, poems, novels, plays, and music. The collection and analysis of primary sources is central to historical research.
What makes a good primary source?
“Primary sources” are the raw materials of history — original documents and objects which were created at the time under study. They are different from secondary sources, accounts or interpretations of events created by someone without firsthand experience.
Can a textbook be a primary source?
A textbook can either be a secondary or tertiary source and, in seldom cases, a primary source. In most cases, the author of a textbook interprets prescribed theories of a topic and would, therefore, be a secondary source.
Why is a book a secondary source?
Secondary sources were created by someone who did not experience first-hand or participate in the events or conditions you’re researching. For a historical research project, secondary sources are generally scholarly books and articles. A secondary source interprets and analyzes primary sources.
Is the moon a secondary source of light?
Such sources of light are called secondary sources, e.g. the moon, the planets, objects such as humans, animals, plants, etc. These objects are visible due to reflected light. Many of the sources that we see around are secondary sources and most of them are extended sources.
What are the conditions for obtaining good interference pattern?
To set up a stable and clear interference pattern, two conditions must be met: The sources of the waves must be coherent, which means they emit identical waves with a constant phase difference. The waves should be monochromatic – they should be of a single wavelength.
What is the condition of constructive interference?
Constructive interference occurs when the maxima of two waves add together (the two waves are in phase), so that the amplitude of the resulting wave is equal to the sum of the individual amplitudes. Equivalently, the minima of the waves would be aligned.