TeXes Science Practice Test

Which type of telescope uses lenses to focus visible light?

1. Reflecting telescope

2. Refracting telescope

3. Catadioptric telescope

4. Radio telescope

The correct answer is: Refracting telescope

A refracting telescope is designed specifically to utilize lenses for focusing visible light. It achieves this through the arrangement of one or more convex lenses that bend (refract) light rays to a focal point, creating a magnified image. This type of telescope leverages the principles of optics to gather and focus light, making it effective for observing celestial objects such as planets and stars. In contrast, a reflecting telescope utilizes mirrors, rather than lenses, to direct and focus light. The mirrors collect light and reflect it to a focal point, which is a distinct method that differs fundamentally from lens-based systems. Catadioptric telescopes combine both lenses and mirrors to achieve a compact design and improved image quality, but they still rely on mirrors as a crucial component. Lastly, a radio telescope detects radio waves rather than visible light, using large parabolic dishes to collect and focus these longer wavelengths, thus serving an entirely different purpose in astronomy.