Difference Between

AM radio (AM stands for Amplitude Modulation) and PM radio (PM stands for Phase Modulation) are two different types of radio transmission technologies . Both AM and PM radio use electromagnetic waves to transmit audio signals over long distances, but they differ in the way the information is encoded onto the wave. Purposes The primary purpose of AM radio is to transmit low-fidelity audio signals over medium to long distances, while PM radio is designed for transmitting high-fidelity audio signals over shorter distances. Characteristics 1. AM radio: AM radio uses amplitude modulation, where the amplitude (height) of the radio wave is varied in proportion to the audio signal. This makes AM radio susceptible to interference from static electricity and other radio signals. AM radio signals also have a narrower bandwidth compared to PM radio signals, which means they can suffer from frequency crowding. The audio quality of AM radio is usually poorer than that of PM radio due to the ...

A primary source of information is the original document, record, or data generated by an event, experiment, or person. It provides firsthand evidence or direct evidence of an event, without any interpretation or analysis from other sources. Primary sources are often used in historical research, scientific studies, and journalism to capture the raw facts and context of a particular event or phenomenon. Examples of primary sources include: 1. Original documents (e.g., diaries, letters, meeting minutes, legal documents, scientific observations) 2. Historical artifacts (e.g., artwork, tools, clothing) 3. Interviews (e.g., oral histories, personal accounts) 4. Observational data (e.g., field notes, laboratory results) 5. Original research articles (e.g., in scientific journals) A secondary source of information is one that analyzes, interprets, or discusses primary sources. It provides a second layer of interpretation and analysis, often providing context, background information, and cri...