What is the angular magnification of a telescope having objective and eyepiece lenses of a focal lengths 30cm and 3cm respectively?
Answer Details
The angular magnification of a telescope can be calculated using the formula:
m = -fo/fe
where m is the angular magnification, fo is the focal length of the objective lens, and fe is the focal length of the eyepiece.
In this case, the focal length of the objective lens is 30cm, and the focal length of the eyepiece is 3cm. Plugging these values into the formula gives:
m = -30/3 = -10
Therefore, the angular magnification of the telescope is -10. The negative sign indicates that the image formed by the telescope is inverted.
To understand this result, consider that the objective lens forms a real inverted image of the object being viewed. This image is located at a distance equal to the focal length of the eyepiece. The eyepiece then acts as a magnifying glass to further magnify the image. The angular magnification tells us how much larger the image appears through the telescope compared to the naked eye. In this case, the image appears 10 times larger, but inverted, when viewed through the telescope.