Request a call back

Join NOW to get access to exclusive study material for best results

# CBSE Class 12-science Answered

derive an expression for the magnifying power of an astronomical telescope in normal adjustment?
Asked by shijurlytepz | 12 Oct, 2021, 06:56: PM
Expert Answer
Astronomical telescope that is used to provide angular magnification of distanr object is shown in figure.
It has an objective lens of long focal length and greater diameter.
Diameter of eye piece and focal length are smaller than that of objective lens.
Light from a distant object enters the objective and a real image is formed
in the tube at its second focal point. The eyepiece magnifies this image
producing a final inverted image. Distance between objective and eyepiece that is called as tube length is
sum of focal lengths of objective and eye-piece length so that inside the tube focal points of both the lenses coincide.

The magnifying power m is the ratio of the angle β subtended at the eye by image to the angle α
that is subtended by object at the lens.

m = ( β / α )

β ≈ tanβ = h / fe

where h is image height and fe is focal length of eye piece
α ≈ tanα = h / fo
where fo is foacl length of objective lens

hence , we get  magnifying power m as

Answered by Thiyagarajan K | 12 Oct, 2021, 10:21: PM

## Concept Videos

CBSE 12-science - Physics
Asked by kamleshstarone392 | 16 Apr, 2022, 06:26: AM
ANSWERED BY EXPERT
CBSE 12-science - Physics
Asked by shijurlytepz | 12 Oct, 2021, 06:56: PM
ANSWERED BY EXPERT
CBSE 12-science - Physics
Asked by khanhill543 | 31 Dec, 2020, 12:20: AM
ANSWERED BY EXPERT
CBSE 12-science - Physics
Asked by ABHILASHA | 15 Sep, 2020, 06:23: PM
ANSWERED BY EXPERT
CBSE 12-science - Physics
Asked by akgujrati04 | 22 Aug, 2020, 07:06: PM
ANSWERED BY EXPERT
CBSE 12-science - Physics
Asked by mazhartahsildar143 | 02 May, 2020, 01:32: PM
ANSWERED BY EXPERT
CBSE 12-science - Physics
Asked by govtsecschoolnayaganv051 | 24 Feb, 2020, 04:17: PM
ANSWERED BY EXPERT
CBSE 12-science - Physics
Asked by singhalakash8958 | 03 Mar, 2019, 10:11: PM
ANSWERED BY EXPERT
CBSE 12-science - Physics
Asked by vishakhachandan026 | 23 Feb, 2019, 06:15: PM
ANSWERED BY EXPERT
CBSE 12-science - Physics
Asked by mridulabarua05 | 09 Feb, 2019, 01:08: PM
ANSWERED BY EXPERT
Season Break Offer!
Get 60% Flat off instantly.
Avail Now
×