Question 1: Define the term 'Red Shift' in the context of astronomy.

Answer: Red Shift is the phenomenon where light from an object in space is shifted towards longer wavelengths (the red end of the spectrum), indicating that the object is moving away from the observer.

Question 2: Explain the real-world significance of observing Red Shift in distant galaxies.

Answer: Observing Red Shift in distant galaxies provides evidence that the universe is expanding, supporting the Big Bang theory and helping scientists estimate the rate of expansion.

Question 3: Which part of the electromagnetic spectrum is affected by Red Shift?

Answer:

Question 1: Calculate the velocity of a galaxy whose light shows a wavelength shift from 500 nm (rest wavelength) to 550 nm. Use the Red Shift formula v = (Δλ / λ₀) × c, where c = 3.00 × 10^8 m/s.

Answer: Velocity v = [(550 nm - 500 nm) / 500 nm] × 3.00 × 10^8 m/s = (50 nm / 500 nm) × 3.00 × 10^8 m/s = 0.1 × 3.00 × 10^8 m/s = 3.00 × 10^7 m/s

Question 2: A galaxy has a measured redshift (z) of 0.05. Calculate its approximate recession velocity using v ≈ z × c.

Answer: Velocity v ≈ 0.05 × 3.00 × 10^8 m/s = 1.50 × 10^7 m/s

Question 1: Describe a basic experimental setup used to measure the Red Shift of distant galaxies.

Answer: A telescope equipped with a spectrometer is used to observe the light from a galaxy. The spectrometer disperses the light into a spectrum, allowing astronomers to measure the wavelength of specific spectral lines. By comparing these wavelengths to known laboratory values, they determine the amount of Red Shift and thus infer the galaxy's velocity.

Question 2: Identify two variables that must be controlled or measured accurately when conducting observations of Red Shift.

Answer: The accuracy of the wavelength measurement and the calibration of the spectrometer.

Question 3: List two safety precautions that should be considered when using spectrometers and telescopes in astronomical observations.

Answer: Protective measures to prevent eye damage from intense light and ensuring stability of the equipment to prevent accidents or damage.

Question 1: A spectral line from a distant galaxy is observed at 660 nm, while its laboratory wavelength is 650 nm. Calculate the redshift (z) and interpret what this indicates about the galaxy's motion.

Answer: z = (λ_observed - λ_rest) / λ_rest = (660 nm - 650 nm) / 650 nm = 10 nm / 650 nm ≈ 0.015. This indicates the galaxy is moving away from us at a velocity approximately 0.015 × 3.00 × 10^8 m/s ≈ 4.50 × 10^6 m/s.

Question 2: Based on the data provided, discuss how astronomers can estimate the rate of expansion of the universe.

Answer: Astronomers measure the Red Shift of numerous galaxies at different distances. By plotting velocity against distance (via Hubble's Law), they can determine the Hubble constant, which quantifies the rate of expansion of the universe. The greater the Red Shift for distant galaxies, the faster the universe is expanding.

Question 1: Explain how understanding Red Shift is important in developing models of the universe's origin and evolution.

Answer: Red Shift provides evidence that the universe is expanding, supporting the Big Bang theory. By analysing Red Shift data, scientists can estimate the age, size, and rate of expansion of the universe, helping to refine models of its origin and future evolution.

Question 2: Describe a technological advancement that relies on the understanding of Red Shift for its operation.

Answer: The Hubble Space Telescope uses Red Shift measurements to observe distant galaxies, helping scientists determine their velocities and distances, which are essential for studying the universe's expansion.