Home
Class 12
PHYSICS
A Galilean telescope is constructed by a...

A Galilean telescope is constructed by an objective of focal length 50 cm and a eyepiece of focal length 5.0 cm a. find the tube length and magnifying power when it is used to see n object at a large distancei normal adjustment b. if the telescope is to focus an object 2.0 m away from the objective what should be the tube length and angular magnification, the image again forming at infinity?

Text Solution

Verified by Experts

f_0=500cm, f_e=-5cm`
a. `L=f_0-|f_e|(50-5)cm=45cm`
and `m=-f_0/f_e=50/5=10.`
`b. Using the equation `1/v-1/u=1/f` for the objective.
`1/v=1/f_0+1/u`
`=1/(50cm)+1/(-200cm)`
or v=66-67cm`
the tube length `L=v-|f_e-|=(66.67-5)cm`
or, L=61.67cm`
to calculate the angular magnification we assume that the object remains at large distance from the eye. In this case the angular magnification
`m=v/f_e=66.67/5=13.33.`
v is the distance of the first image from the objective which is subsituted for `f_0`.
Promotional Banner

Topper's Solved these Questions

  • OPTICAL INSTRUMENTS

    HC VERMA|Exercise Question for short Answer|12 Videos

  • OPTICAL INSTRUMENTS

    HC VERMA|Exercise Objective -1|11 Videos

  • OPTICAL INSTRUMENTS

    HC VERMA|Exercise Exercises|23 Videos

  • MAGNETIC PROPERTIES OF MATTER

    HC VERMA|Exercise Exercise|9 Videos

  • PERMANENT MAGNETS

    HC VERMA|Exercise Exercise|25 Videos

Similar Questions

Explore conceptually related problems

A small telescope has an objective lens of focal length 144 cm and eyepiece of focal length 6.0 cm. What is the magnifying power of the telescope ? What is the separation between the objective and the eyepiece?

A small telescope has an objective lens of focal length 140 cm and eyepiece of focal length 5.0 cm. What is the magnifying power of the telescope for viewing distant objects when (a) the telescope is in normal adjustment and (b) the final image is formed at least distance of distinct vision ?

a. A gaint refracting telescope at an observatory has an objective lens of focal length 15 m. If an eyepiece of focal length 1.0 cm is used, What is the angular magnification of the telescope ?

A small telescope has an objective lens of focal length 150 cm and eyepiece of focal length 5 cm. What is the magnifying power of the telescope for viewing distant object in normal adjustment? If this telescope is used to view a 100 m tall Also tower 3 km away, what is the height of the image of the tower formed by the objective lens?

A small telescope has an objective lens of focal length 140 cm and eyepiece of focal length 5.0 cm. What is the megniftying power of the telescope for viewing distant objects when (a) the telescope is in normal adjustment (i.e, when the final image is at infinity ) (b) the final image is formed at the least distance of distinct vision (25cm) ?

A compound microscope has an objective of focal length 1 cm and an eyepiece of focal length 2.5 cm. An object has to be placed at a distance of 1.2 cm away from the objective for normal adjustment. a.Find the angular magnification. b.Find the length of the microscope tube.

A small telescope has an objective lens of focal length 125 cm and an eyepiece of focal length 2 cm. What is the magnification of the telescope? What is the separation between the objective and eyepiece? Two stars separated by 1' will appear at what separation when viewed through the telescope?

A microscope has an object and eyepiece of focal lenghts 5 cm and 50 cm respectively with tube length 30 cm. Find the magnification of the microscope in the (i) near point and (ii) normal focusing.

An angular magnification (magnifying power ) of 30x is desired using on objective of focal length 1.25 cm and an eyepiece of focal length 5cm. How will you set up the compound microscope ?