A Level 9.3 Cosmology Quiz

What happens to the wavelength of light from a star moving towards the Earth compared to when the star is stationary?

• The wavelength becomes shorter

• The wavelength becomes longer

• The wavelength remains the same

• The wavelength disappears

What is the Doppler effect?

• A change in the observed frequency of a wave when the source or observer is moving

• The disappearance of a wave when a source moves away from the observer

• The increase in the speed of light when a source moves towards an observer

• A change in the speed of a wave when the source is stationary

Why does the pitch of an emergency vehicle's siren appear higher as it approaches and then lower as it passes by?

• Because the speed of the vehicle changes

• Because the frequency of the siren changes

• Because the Doppler effect causes a change in the observed frequency

• Because the distance between the vehicle and observer increases

How can the Doppler effect be used in astrophysics?

• To measure the velocity of stars in a binary system

• To determine the color of stars

• To calculate the age of stars

• To identify the elements present in a star

What is the term used to describe the shift to longer wavelengths in the spectrum when the source of light moves away from the observer?

• Blue shift

• Red shift

• Green shift

• Yellow shift

What happens to the frequency of the waves when the source moves towards the observer?

• It decreases

• It remains the same

• It increases

• It becomes zero

How is the Doppler shift, z mathematically represented?

• λ / Δλ

• c / v

• Δλ / λ

• f / Δf

What is the Doppler shift in wavelength when the source moves away from the observer?

• +v / c

• -v / c

• v / f

• -f / c

According to the document, what causes a blue shift in the spectrum?

• The source moving away from the observer

• The source moving at a constant speed

• The source moving towards the observer

• The source remaining stationary

What is the change of frequency Δf when the source moves towards the observer?

• Δf = -f * (v / c )

• Δf = f * (v / c)

• Δf = λ * (v / c )

• Δf = -λ * (v / c )