The magnifying power of an astronomical telescope in the normal adjustment position is 100. The distance between the objective and eye piece is 101 cm. Calculate the focal lengths of objective and eye piece.

An astronomical telescope is designed to have a magnifying power of 50 in normal adjustment. If the length pf the tube is 120cm, find the powers of objective and eye piece.

Kanchan while driving her scooty sees a woman behind driving a moped through his rear view mirror. She sees that her saree is almost touching the wheels of the vehicle. She stops her and alert that it may cause a severe accident.
Read the above passage and answer the folllowing questions:
(i) What values do you observe in Kanchan?
(ii) Name the mirror used in rear view in scooty. Draw a ray diagram for the same.

Answer the following questions.
(i) You have learnt that plane and convex mirrors produce virtual images of objects. Can they produce real images under some circumstances? Expalin.
(ii) A virtual image, we always say, cannot be caught on a screen. Yet when we see a virtual image, we are obviously bringing it on to the screen (i.e. the retina) of our eye. Is there a contradiction?
(iii) A diver under water, looks obliquely at a fisherman standing on the bank of a lake. Would the fisherman look taller or shorter to the diver than what he actually is?
(iv) Does the apparent depth of a tank of water change, if viewed obliquely? If so, does the apparent depth increase or decrease?

(i) In a double slit experiment using light of wavelength 600 nm, the angular width of the fringe formed on a distant screen is \(0.1^o\) . Find the spacing between the two slits.
(ii) Light of wavelength 5000\(\dot { A } \) propagating in air gets partly reflected from the surface of water. How will the wavelengths and frequencies of the reflected and refracted light be affected?

(i) Draw a diagram showing the 'Young's arrangement' for producing 'a sustained interference pattern'. Hence obtained the expression for the width of the interference fringes obtained in this pattern.
(ii) If the principal source point S were to be moved a little upwards, towards the slit SI from its usual symmetrical position, with respect to the two slits S₁ and S₂, discuss how the interference pattern, obtained on the screen, would get affected

(a) In Young's double slit experiment, describe briefly how bright and dark fringes are obtained
on the screen kept in front of a double slit. Hence obtain the expression for the fringe width.
(b) The ratio of the intensities at minima to the maxima in the Young's double slit experiment is 9 : 25. Find the ratio of the width of the slits

School arrange an educational trip to Kavalur in Tamil Nadu where an observatory having Indias largest telescope. On hearing this, the whole class  got excited and left for their way to kavalur. In the observatory, the physics teacher' was explaining about the type of telescope, with diameter of objective (2.34 m) and several other details. Everyone was ready to look through the telescope.
(i) What type of telescope is the teacher referring to?
(ii) Mention any two advantages of this telescope
(iii) Why are such a field trips important?

A screen is placed 2m away from the single narrow slit. Calculate the slit width if the first minimum lies 5mm on either side of the central maximum. Incident plane waves have a wavelength of \(5000\mathring { A } \)

What should be the width of each slit to obtain 10 maxima of the double slit interference pattern within the central maximum of single slit diffraction pattern?