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Question 19M.3.SL.TZ2.14aii

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Date May 2019 Marks available [Maximum mark: 2] Reference code 19M.3.SL.TZ2.14aii
Level SL Paper 3 Time zone TZ2
Command term Calculate Question number aii Adapted from N/A
aii.
[Maximum mark: 2]
19M.3.SL.TZ2.14aii

The Hubble constant is 2.3 × 10-18 s-1.

(aii)

A line in the hydrogen spectrum when measured on Earth has a wavelength of 486 nm. Calculate, in nm, the wavelength of the same hydrogen line when observed in the galaxy’s emission spectrum.

[2]

Markscheme

Δ λ = « λ 0 v c = 4.86 × 10 − 7 × 3.48 × 10 6 3 × 10 8 = » 5.64«nm»  ✔

observed λ = «486 + 5.64 =» 492 «nm»✔

Examiners report

Many candidates subtracted the change in wavelength and obtained a blue shift. Others were unsure which wavelength λo is in the data book equation. But correct answers were common.

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