Question

Topic

In your initial discussion post, identify the pros and cons of using mirrors versus lenses in each of the following applications:

• a large, ground-based, astronomical telescope
• a small “spy” scope
• a terrestrial telescope designed only to read license plates

I need detailed typed response for above discussion topic, If you are sure then do it otherwise don't bother yourself.

Answer 1

First of all, I want to tell that refracting type telescopes came first before the reflecting type telescopes. Refracting type telescopes are those which use lenses to produce image whereas reflecting type telescopes are those which use mirrors to produce image. As reflecting type telescope has discovered later , it reduces and cures the drawbacks of refracting type.

A large ground based telescopes, spy telescope and terrestrial telescopes are available in refracting as well as refracting type.Then , mirrors vs lens comaparison can be described as:

ADVANTAGES OF USING MIRRORS:

1)Mirrors are free from spherical aberration( outer and inner rays through lens don't meet at the same point on axis) as well as chromatic aberration( different wavelength rays or different colour rays do not meet at same point or focus)

2) Telescopes using mirrors have large light gathering power(in order to obtain a bright image of the object) and high resolving power(so as to observe it's finer details)

4) Mirrors are cheaper than lenses.

DISADVANTAGE OF USING MIRRORS:

1) Telescopes using mirrors have high cost maintenance. The mirrors need to clean periodically as these are open telescopes.

2)The polishing of mirror needs to be maintained after a period of time to obtain clear image.

ADVANTAGES OF USING LENSES:

1) Telescopes using lenses are easy to handle.

2) They don't require high cost of maintenance.

DISADVANTAGES OF LENSES :

1) Chromatic aberration appears while using lenses.

2) Spherical aberration appears while using lenses.

3) Initial setup cost of telescope using lenses are high as lenses are of more cost as compared to mirrors.

4)They have low light gathering power.