Which of the following is correct? (A) The size of image on the retina is roughly proportional to the angle subtended by the object on the eye. This angle is known as visual angle. The optical instruments are used to increase the visual angle (B) In normal adjustment, eye is least strained and final image is formed at infinity (c) The magnifying power is written with a unit X (D) All options are correct

Why does a tower appear larger and larger to a person approaching it ? 1. The angle subtended by the tower at the eye increases. 2. The focal length of eye increases. 3. The size of the image on the retian of eye increases. Select the correct answer using the code given below:

In case of a compound microscope which of the following Statements is/are correct ? 1. The focal length of the eye piece is larger than the focal length of the objective 2. The focal length of the eye piece is smaller than the focal length of the objective 3. The image produced in a normal optical microscope is real 4. The image produced in a normal optical microscope is virtual Select the correct answer using the code given below:

An optical instrument uses eye-lens of power 16 D and objective lens of power 50D and has a tube length of 16.25 cm. Name the optical instrument and calculate its magnifying power if forms the final image at infinity.

A telescope consists of two lenses of focal lengths 0.3 m and 3 cm respectively. It is fucussed on moon which subtends an angle of 0.5^@ at the obejctive. Calculate the angle subtended at the eye by the final image in normal adjustment of the telescope.

A simple astronomical telescope is designed using two convex lenses of focal lengths 1 m and 0.05 m. Find the magnifying power when the instrument is used to view a distant object if the final image is formed (a) at a great distance, (b) at a distance of 0.25 m from the eye-piece.

A small telescope has an objective lens of focal length 140 cm and an 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 (i.e, when the final image is at infinity ), (b) The final image is formed at the least distance of distinct vision (25 cm )