Exploring the Cosmos - Degree Exam 2013 - Mapping the universe
1. A Schmidt-Cassegrain telescope is one that has?
Only mirrors.
A corrector plate and a primary mirror only.
Only lenses.
A corrector plate, a primary mirror and a secondary mirror.
2. Why are astronomers interested in measuring light at different parts of the electromagnetic spectrum?
Different parts of the spectrum provide different information.
Stars emit mainly ultraviolet radiation.
Because visible light is hard to detect on Earth.
Because in vacuum light travels at different speeds at different wavelengths.
3. What does the frequency of light mean?
How bright the light will be.
The number of times the wave cycle repeats every second.
The distance it will travel in 1 second.
The distance from one maximum to another.
4. The energy of a photon can be expressed by
E=f/λ.
E=cλ.
E=hc.
E=hf.
5. What is the purpose of the objective lens in a refracting telescope?
To interfere the incoming light.
To diffract the incoming light.
To focus the incoming light.
To change the speed of the incoming light.
6. If a refracting telescope has an objective lens with a focal length of 300cm and has an eyepiece with a focal length of 3cm, the magnification is?
M = 3/300.
M = 1/100.
M = 100.
M = 300.
7. Active optics is used in modern telescopes to
change the shape of the primary mirror to correct for atmospheric disturbances.
change the detector sensitivity for measuring different wavelengths.
maximise the light gathering power of the telescope.
change the focal length of the primary mirror for different astronomical objects.
8. The Earth’s atmosphere is responsible for which three phenomena in observational astronomy?
Atmospheric refraction, Atmospheric scattering, and Atmospheric absorption.
Wave particle duality, Atmospheric scattering, and Atmospheric absorption.
Atmospheric diffraction, Chromatic aberration, and Atmospheric scattering.
Atmospheric scattering, Spherical aberration, and Atmospheric refraction.
9. For what reason is interferometry used when using multiple telescopes to observe astronomical objects?
To measure different frequencies of light simultaneously.
To remove the effect of light pollution.
To reduce the magnification.
To increase the resolving power of the detector.
10. Gravitational wave detectors aim to measure the radiation emitted by accelerating masses by
using multiple radio telescopes around the world.
using the James Webb Space Telescope.
detecting Cherenkov radiation with photomultiplier tubes.
using long-baseline laser interferometers.
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