GENERAL KNOWLEDGE

GK

THE UNIVERSE

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
A shift toward longer wavelengths of the spectral lines emitted by a celestial object that is caused by the object moving away from the earth.
A
BLUE SHIFT
B
EXPANSION
C
CONTRACTION
D
RED SHIFT
Explanation: 

Detailed explanation-1: -As an object moves away from us, the sound or light waves emitted by the object are stretched out, which makes them have a lower pitch and moves them towards the red end of the electromagnetic spectrum, where light has a longer wavelength. In the case of light waves, this is called redshift.

Detailed explanation-2: -This effect is called the doppler shift. If the object is coming toward you, the light is shifted toward shorter wavelengths, blue shifted . If the object is going away from you, the light is shifted toward longer wavelengths, red shifted . The amount of shift is bigger if the emitting object is moving faster.

Detailed explanation-3: -Doppler shift So, if a star is moving towards Earth, it appears to emit light that is shorter in wavelength compared to a source of light that isn’t moving. Because shorter wavelengths correspond to a shift towards the blue end of the spectrum, this is called blueshift.

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