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Question 18M.3.HL.TZ2.c

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Date May 2018 Marks available [Maximum mark: 3] Reference code 18M.3.HL.TZ2.c
Level HL Paper 3 Time zone TZ2
Command term Comment Question number c Adapted from N/A
c.
[Maximum mark: 3]
18M.3.HL.TZ2.c

The diagram represents a simple optical astronomical reflecting telescope with the path of some light rays shown.

It is proposed to build an array of radio telescopes such that the maximum distance between them is 3800 km. The array will operate at a wavelength of 2.1 cm.

Comment on whether it is possible to build an optical telescope operating at 580 nm that is to have the same resolution as the array.

[3]

Markscheme

«use of  1.22 λ d  to get» resolution of 6.7 × 10–9 «rad»

5.8 × 10 − 7 6.7 × 10 − 9 = 87 «m»

some reference to difficulty in making optical mirrors/lenses of this size

 

Allow  5.8 × 10 − 7 5.5 × 10 − 9 = 105 «m»

[3 marks]

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