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Question 23M.3.HL.TZ1.17

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Date May 2023 Marks available [Maximum mark: 4] Reference code 23M.3.HL.TZ1.17
Level HL Paper 3 Time zone TZ1
Command term Determine, Estimate, State Question number 17 Adapted from N/A
17.
[Maximum mark: 4]
23M.3.HL.TZ1.17

A distant galaxy emits light of wavelength 486 nm. The light received on Earth has wavelength 512 nm.

(a)

Determine the recession speed of the galaxy.

[2]

Markscheme

vc=512-486486 ✓

⇒ v = 1.6 × 104 «km s−1»

 

Accept 0.053 c.

Accept answer in m s−1.

Award [2] for BCA.

Examiners report

Hubble constant. Well done. The importance of the value of Hubble constant is well known by students attempting the Astrophysics option.

(b)

Estimate the distance to the galaxy in pc. Take the Hubble constant as 72 km s−1 Mpc−1.

[1]

Markscheme

d = vH = 1.6×10472 = 222 ≈ 220 «Mpc»

 

ECF from (a).

(c)

Astrophysicists continue to seek an accurate value of the Hubble constant. State the importance of this constant for cosmology.

[1]

Markscheme

it is important because it is related to the age of the universe ✓

it is important in testing models of the universe ✓

it is important for determining distances ✓