Astrophysics 1 - Basics of Refracting Telescopes Flashcards
What is a lens?
A lens is a piece of glass which refracts radiation when it passes through the glass.
What are the two types of telescopes, and what is the difference between them?
Optical telescopes - use visible light to produce images.
Non-optical telescopes - use the non visible part of the EM spectrum to produce images.
What are the two main types of optical telescopes?
Refracting telescopes
Reflecting telescopes
Describe a refracting telescope.
Hint:
What does it consist of?
How does it produce images?
Disadvantages.
Aberration type?
Refracting telescopes consist of two converging lenses in a normal adjustment.
They produce images by refracting radiation through glass/lenses.
They are expensive, easy to distort, and expensive to manufacture.
They produce images which have a chromatic aberration.
Describe a reflecting telescope.
Hint:
What does it consist of?
How does it produce images?
Advantages over refracting telescopes?
Aberration type?
Reflecting telescopes consist of two mirrors and a converging lens in a Cassegrain arrangement.
They produce images by reflecting radiation off the glass.
They are cheaper, can be supported easily, and easy to manufacture.
They produce images which have a spherical aberration.
What is the difference between a mirror and a lens?
Mirrors are pieces of glass that reflect light.
Lenses are pieces of glass that refract light.
In a lens diagram, where is the receiver placed?
The receiver is placed on the right hand side of the glass.
In a lens diagram, where is the emitter placed?
The emitter is placed on the left hand side of the glass.
What is the optical axis, or the principal axis?
This is the line passing through the centre of the lens, perpendicular to the lens.
In a lens diagram, what is an object, and what is an image?
An object is the thing that gives off the light.
An image is the thing that we see.
What are the two types of lenses?
Convex lenses
Concave lenses
Describe convex lenses.
They bring rays together at a focus. They are converging lenses. (Line with an arrow at each end).
Describe concave lenses.
Theses spread rays out. They are diverging lenses. (Line with a Y at each end).
