Posted by **Matrix School 1** on Friday, July 24, 2009 at 12:06pm.

An astronomical telescope consists an objective of focal lenght 100cm and an eyepiece of focal lenght 8cm.

calculate the angular magnification of the telescope and also determine the distance between the two lenses.

- Geometric & Wave Optics -
**MathMate**, Saturday, July 25, 2009 at 9:16am
For astronomical telescopes, the objects are at infinity, so parallel rays reach the objective. The eye-piece is therefore placed at a distance from the objective equal to the focal length. At this location, the magnification is equal to the quotient of the focal lengths.

Magnification

= 100 cm / 8 cm

= 12.5 times.

Note: eye-pieces usually have focal lengths in the millimetres range, so it is likely that the focal length of the eye-piece is 8 mm., in which case

Magnification

= 100 cm /8 mm

= 125 times.

- Geometric & Wave Optics -
**Anonymous**, Thursday, February 3, 2011 at 3:25pm
1. An object,30mm high ,is 90mm from a convex lens. The focal length is 60mm det the positive height an nature of the image. Draw an accurate diagram for the formation of the image. 2.calculate its magnification?

## Answer this Question

## Related Questions

- Geo. & Wave Optics - An astronomical telescope consists an objective of focal ...
- Physics Help Please --- Telescope - An astronomical refracting telescope is ...
- physics - A laboratory (astronomical) telescope is used to view a scale that is ...
- physics - A telescope that has a 100 cm focal length objective and a 3.00 cm ...
- Physics - A telescope has a magnification of 20 and consists of two converging ...
- physics - Galileo's first telescope used a convex objective lens with a focal ...
- PHYSICS - An astronomical telescope has an objective lens of 80cm and an ...
- physics - The Yerkes refracting telescope has a 1 m diameter objective lens of ...
- physics-lenses - a certain Galilean telescope has a magnification of 2 times. if...
- Physics: Focal length why is my answer wrong? - An old refracting telescope in a...

More Related Questions