Technology in the 1920s
Radio and Television Transmission
A useful technological advancement of the 1920s was the invention of radio and television transmission. Before 1920, radio transmission consisted of a series of dots and dashes, transmitted by inefficient machines. The credit for inventing the present-day radio/television transmission goes to Ernst Alexanderson, a Swedish-American engineer. After rigorous experimentation and hard work, he invented a high-frequency alternator for the first time, with which transmission of radio waves became successful. A few years later, he developed a scanning disk and high-frequency neon lamps for television transmission.
A useful technological advancement of the 1920s was the invention of radio and television transmission. Before 1920, radio transmission consisted of a series of dots and dashes, transmitted by inefficient machines. The credit for inventing the present-day radio/television transmission goes to Ernst Alexanderson, a Swedish-American engineer. After rigorous experimentation and hard work, he invented a high-frequency alternator for the first time, with which transmission of radio waves became successful. A few years later, he developed a scanning disk and high-frequency neon lamps for television transmission.
Traffic Lights
The 1920's lead to change by the numerous practical inventions that are still frequently used today. One of these inventions was the traffic light created in 1920. This invention by Garrett Morgan was in use throughout North America until all manual traffic signals were replaced by the automatic red, yellow, and green-light traffic signals currently used around the world. It has since helped society as the roads nowadays are much more safer by letting pedestrians cross the roads in a cautious manner and has saved thousands of lives by preventing a huge number of car crashes. The traffic light also maintains orderly traffic flow which is essential in many communities.
The Lie Detector
The Lie detector (also known as the polygraph) was invented by John Larson in 1921. When a person lies, the lying causes a certain amount of stress that creates changes into many automatic physiological reactions. During a lie detection test, the operator asks a series of control questions that set the pattern of how a person reacts when giving true and false answers. A number of different sensors are secured to the body, and as the polygraph measures differences in breathing, pulse, perspiration and blood pressure, pens record the information on graph paper. If the measurements were high, then an alarm would go off, implying that the person was lying.