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