Draw a ray diagram of a reflecting type telescope. State two advantages of this telescope over a refracting telescope.
The correct answer and explanation is :
Here is the ray diagram of a reflecting telescope. It shows how light from a distant object is first captured by the primary mirror, which reflects the light to the secondary mirror, which further directs the light towards the eyepiece for observation.
Two Advantages of a Reflecting Telescope over a Refracting Telescope:
- Absence of Chromatic Aberration: Reflecting telescopes do not suffer from chromatic aberration, which is the failure of a lens to focus all colors of light at the same point. In a refracting telescope, the glass lens bends different wavelengths (colors) of light by different amounts, leading to color fringing around bright objects. A reflecting telescope uses mirrors, which do not have this issue since they reflect all wavelengths of light uniformly.
- Larger Apertures: Reflecting telescopes can be made much larger than refracting telescopes. The primary mirror can be fabricated in large sizes to gather more light, which allows for better resolution and the ability to observe fainter and more distant objects. Large lenses are difficult and expensive to manufacture without defects, while large mirrors can be supported more easily, making large reflecting telescopes more practical and affordable.
Explanation:
Reflecting telescopes work on the principle of reflection. The primary mirror gathers incoming light and focuses it onto the secondary mirror, which then redirects the light to the eyepiece or camera. This design allows for the construction of large telescopes, which is one of the main reasons why most professional observatories use reflecting telescopes. Additionally, the absence of lenses eliminates chromatic aberration, a significant problem in refracting telescopes. Furthermore, mirrors can be made of materials like glass or metal that can be supported from behind, allowing them to be much larger than the lenses used in refracting telescopes. This is crucial for astronomical observations, as larger telescopes can capture more light and provide clearer, more detailed images of distant celestial bodies.