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Question
Astronomers can tell whether a star is approaching or receding from the earth . Identify by which of the following method they can predict this ?
Astronomers can tell whether a star is approaching or receding from the earth . Identify by which of the following method they can predict this ?
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Solution
The correct option is C Doppler shift of the starlight
To predict the movement of a star, we compare the spectra of elements found in star (H, He Na etc.), first spectra which are obtained from star and second spectra from laboratory. If spectral lines of the spectra obtained from star, are shifting towards red end (called red shift) then star is going away from earth and if shifting is towards blue (called blue shift), then star is approaching the earth. This is Doppler's shift.
To predict the movement of a star, we compare the spectra of elements found in star (H, He Na etc.), first spectra which are obtained from star and second spectra from laboratory. If spectral lines of the spectra obtained from star, are shifting towards red end (called red shift) then star is going away from earth and if shifting is towards blue (called blue shift), then star is approaching the earth. This is Doppler's shift.
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line
emitted by hydrogen in a star is found to be red shifted by 15 Å.
Estimate the speed with which the star is receding from the Earth.