Advertisements
Advertisements
प्रश्न
Answer the following question.
Why is prism binoculars preferred over traditional binoculars? Describe its working in brief.
Advertisements
उत्तर
- Traditional binoculars use only two cylinders. Distance between the two cylinders can’t be greater than that between the two eyes. This creates a limitation of the field of view.
- A prism binocular has two right-angled glass prisms that apply the principle of total internal reflection.
- The incident light rays are reflected internally twice giving the viewer a wider field of view. For this reason, prism binoculars are preferred over traditional binoculars.
Working:
Prism binoculars
- The prism binoculars consist of 4 isosceles, right-angled prisms of a material having a critical angle less than 45°.
- The prism binoculars have a wider input range compared to traditional binoculars.
- The light rays incident on the prism binoculars, first get total internally reflected by the isosceles, right-angled prisms 1 and 4.
- These reflected rays undergo another total internal reflection by prisms 2 and 3 to form the final image.
APPEARS IN
संबंधित प्रश्न
The diagram below shows a point source P inside a water container. Four rays A, B, C, D starting from the source P are shown up to the water surface
1) Show in the diagram the path of these rays after striking the water surface.
The Critical Angle for the water-air surface is 48°.
2) Name the phenomenon which the rays B and D exhibit.
The figure shows a ray of light falling normally on the face AB of an equilateral glass prism having refractive index`3/2`, placed in water of refractive index `4/3`.Will this ray suffer total internal reflection on striking the face AC? Justify your answer.
Angle of deviation is the angle which the ______ ray makes with the direction of ______ray.
What do you understand by the deviation produced by a prism? Why is it caused?
Total internal reflection occurs only when a ray of light passes from a ______ medium to a ______ medium.
Write the relation between the refractive index and critical angle for a given pair of optical media?
The observation made by Swarali while doing the experiment is given below. Based on these write answers to the questions:
Swarali found that the light ray travelling from the denser medium to rarer medium goes away from the normal. If the angle of incidence (i) is raised by Swarali, the angle of refraction (r) went on increasing. However, after certain value of the angle of incidence the light ray is seen to return back into the denser medium.
Questions:
- What is the specific value of∠i called?
- What is the process of reflection of incident rays into denser medium called?
- Draw the diagrams of three observations made by Swarali.
Define critical angle for a given medium.
Plot a graph between
Angle of incidence versus angle of reflection,
Name the principle on the basis of which optical fibres work.
How does a ray of light bend when it travels from denser to rarer medium.
How are critical angles related to the refractive index of the medium?
State one factor on which a critical angle for a given pair of media depends. The critical angle for the glass-air interface is 45° for the yellow light. Will it be equal to, less than or greater than 45° for (i) red light, (ii) blue light?
PQ and PR are two light rays emerging from the object as shown in the figure below:
(i) What is the special name given to the angle of incidence (∠PQN) of ray PQ?
(ii) Copy the ray diagram and complete it to show the position of the image of the object P when seen obliquely from above.
(iii) Name the phenomenon that occurs if the angle of incidence ∠PQN is increased still further.
Choose the correct option.
Consider the following phenomena/ applications: P) Mirage, Q) rainbow, R) Optical fibre and S) glittering of a diamond. Total internal reflection is involved in
A spherical marble, of refractive index 1.5 and curvature 1.5 cm, contains a tiny air bubble at its centre. Where will it appear when seen from outside?
Which one of the following is NOT the correct formula for refractive index of glass w.r.t. air (aμg) (i = angle of incidence, r = angle of refraction)
For a ray of light, the critical angle is minimum when it travels from ______.
The outer concentric shell in optic fiber is called ______.
A bundle of glass threads, each of which is capable of transmitting messages using light waves is called ______.
Optical Fibres are based on the phenomenon of dispersion.
A light is entering from one medium refractive index `("RI" =5/3)` to another medium at an angle 30°. The angle of refraction for other medium is sin-1 `(5/6)`. then the increase in angle of incidence is ______ such that the ray of light reflected back into the same medium.
A ray of light passes from vacuum into a medium of refractive index µ, the angle of incidence is found to be twice the angle of refraction. Then the angle of incidence is ______.
Small air bubbles rising up a fish tank appear silvery when viewed from some particular angle is due to the ______.
An endoscope uses optic fiber to transmit high resolution images of internal organs without loss of information. The principle of light that is used by the optic fiber is based on ______.
State two differences between normal reflection and total internal reflection.
