Question

How has the Doppler effect and the redshift of stars and galaxies indicated that the universe is expanding?

A: The Doppler effect says that the higher the frequency of waves, the further an object is moving from the observer. The color red has the shortest wavelength.

B: The Doppler effect says that the lower the frequency of waves, the faster an object is moving toward the observer. The color red has the longest wavelength.

C: The Doppler effect says that the frequency of sound or light waves is affected by whether the emitting object is moving toward or away from the observer. The color red has the longest wavelength.

D: The Doppler effect says that the frequency of sound or light waves determines the color of an object. The color red has the longest wavelength.

Answer 1

B is the answer because wavelengths from far away are red-shifted and short ones are blue-shifted

Answer 2

Option C

Step-by-step explanation:

As per the doppler's effect, when an object in the universe move at a fast speed away from the observer, its possesses a high wavelength as compared to its original wavelength.

Since red light has the highest wavelength, any object's wavelength moving towards a high values is said to be red shifted.

Thus, the higher the wavelength, the lower will be the frequency of an object and hence it moves at a faster speed away from the observer and hence the universe is said to be expanding.

Thus, option C is correct.