An amateur astronomer decides to build a telescope from a...

Name: Problem 100, Chapter 26: Physics
Uploaded: 2020-05-05T13:31:43-08:00
Duration: 2 min 8 s
Channel: Adnan Gill
Description: An amateur astronomer decides to build a telescope from a discarded pair of eyeglasses. One of the lenses has a refractive power of 11 diopters, and the other has a refractive power of 1.3 diopters. (a) Which lens should be the objective? (b) How far apart should the lenses be separated? (c) What is the angular magnification of the telescope?

An amateur astronomer decides to build a telescope from a discarded pair of eyeglasses. One of the lenses has a refractive power of 11 diopters, and the other has a refractive power of 1.3 diopters. (a) Which lens should be the objective? (b) How far apart should the lenses be separated? (c) What is the angular magnification of the telescope?

Key Concepts

Refractive Power and Focal Length

Refractive power, measured in diopters, is the measure of a lens's ability to converge or diverge light. It is inversely related to the focal length of the lens, meaning that higher diopters correspond to a shorter focal length and lower diopters to a longer focal length. This relationship is crucial in determining the appropriate roles of lenses in optical systems.

Objective and Eyepiece in Telescopes

In a refracting telescope, the objective lens is responsible for gathering light and providing a real image of a distant object, while the eyepiece lens magnifies that image for the observer. Typically, the objective lens is chosen to have a longer focal length to collect more light over a wider area, making it suitable for capturing distant details.

Lens Separation in Telescopes

The separation between the objective and the eyepiece in a telescope is generally determined by the sum of their focal lengths when the instrument is set to view distant objects (essentially at infinity). This configuration allows the real image produced by the objective to be properly magnified by the eyepiece.

Angular Magnification of Telescopes

Angular magnification is the factor by which a telescope increases the apparent angular size of an object. In refracting telescopes, it is calculated by taking the ratio of the focal lengths of the objective and the eyepiece (with a negative sign indicating image inversion). This concept is key to understanding how telescopes enhance visual details of distant objects.

Transcript

Please give Ace some feedback