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Question 18N.2.HL.TZ0.5b.ii

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Date November 2018 Marks available [Maximum mark: 3] Reference code 18N.2.HL.TZ0.5b.ii
Level HL Paper 2 Time zone TZ0
Command term Calculate Question number b.ii Adapted from N/A
b.ii.
[Maximum mark: 3]
18N.2.HL.TZ0.5b.ii

A low-pressure hydrogen discharge lamp contains a small amount of deuterium gas in addition to the hydrogen gas. The deuterium spectrum contains a red line with a wavelength very close to that of the hydrogen red line. The wavelengths for the principal lines in the visible spectra of deuterium and hydrogen are given in the table.

Light from the discharge lamp is normally incident on a diffraction grating.

(b.ii)

Calculate the angle between the first-order line of the red light in the hydrogen spectrum and the second-order line of the violet light in the hydrogen spectrum.

[3]

Markscheme

2 × 4.1 × 10−7 = 1.9 × 10−6 sin θv seen

OR

6.6 × 10−7 = 1.9 × 10−6 sin θr seen ✔

 

θv = 24 − 26 «°»

OR

θr = 19 − 20 «°» ✔

 

Δθ = 5 − 6 «°» ✔

 

For MP3 answer must follow from answers in MP2

For MP3 do not allow ECF from incorrect angles

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