taajuussiirtymän

Taajuussiirtymä, also known as frequency shift, refers to the change in the observed frequency of a wave caused by the relative motion between the source of the wave and an observer. This phenomenon is a fundamental concept in physics and is most commonly associated with the Doppler effect. When a source emitting waves, such as sound or light, is moving towards an observer, the waves are compressed, resulting in a higher observed frequency. Conversely, if the source is moving away from the observer, the waves are stretched, leading to a lower observed frequency.

The magnitude of the frequency shift depends on the relative speed between the source and the observer, as well as the speed of the wave itself. For sound waves, this effect is readily noticeable. For example, the pitch of a siren on an emergency vehicle appears to rise as it approaches and then fall as it moves away. In the case of light waves, a shift towards higher frequencies is termed a blueshift, indicating that the light source is moving towards the observer. A shift towards lower frequencies is called a redshift, signifying that the light source is moving away.

Astronomers extensively use the redshift of light from distant galaxies to determine their recession velocity and understand the expansion of the universe. This principle also finds applications in various technologies, including radar systems for measuring speed, medical ultrasound for imaging blood flow, and satellite communication. The mathematical description of the Doppler effect provides a quantitative understanding of the observed frequency shift under different conditions.