Advertisements
Advertisements
प्रश्न
Explain red shift and blue shift in Doppler Effect.
Advertisements
उत्तर
If the spectral lines of the star are found to shift towards red end of the spectrum (called redshift) then the star is receding away from the Earth. If the spectral lines of the star are found to shift towards the blue end of the spectrum (called blue shift) then the star is approaching Earth.
APPEARS IN
संबंधित प्रश्न
A narrow sound pulse (for example, a short pip by a whistle) is sent across a medium. (a) Does the pulse have a definite (i) frequency, (ii) wavelength, (iii) speed of propagation? (b) If the pulse rate is 1 after every 20 s, (that is the whistle is blown for a split of second after every 20 s), is the frequency of the note produced by the whistle equal to 1/20 or 0.05 Hz
In discussing Doppler effect, we use the word "apparent frequency". Does it mean that the frequency of the sound is still that of the source and it is some physiological phenomenon in the listener's ear that gives rise to Doppler effect? Think for the observer approaching the source and for the source approaching the observer.
State the expression for apparent frequency when listener is stationary and source is moving towards the listener.
What is meant by the Doppler effect?
Discuss the following case-
Observer in motion and Source at rest.
- Observer moves towards Source
- Observer resides away from the Source
An observer moves towards a stationary source of sound with a velocity one-fifth of the velocity of sound. The percentage increase in the apparent frequency heard by the observer will be ______.
If a star appearing yellow starts accelerating towards the earth, its colour appears to be turned ______.
A source and a detector move away from each other in absence of wind with a speed of 20 m/s with respect to the ground. If the detector detects a frequency of 1800 Hz of the sound coming from the source, then the original frequency of the source considering the speed of sound in air 340 m/s will be ______ Hz.
The frequency of echo will be ______ Hz if the train blowing a whistle of frequency 320 Hz is moving with a velocity of 36 km/h towards a hill from which an echo is heard by the train driver. The velocity of sound in air is 330 m/s.
The pitch of the whistle of an engine appears to drop by 20% of its original value when it passes a stationary observer. If the speed of sound in the air is 350 m/s, then the speed of the engine (in m/s) is ______.
