Plus Two Physics Chapter Wise Previous Questions Chapter 9 Ray Optics and Optical Instruments is part of Kerala Plus Two Physics Chapter Wise Previous Questions and Answers Kerala. Here we have given Plus Two Physics Chapter Wise Questions and Answers Chapter 9 Ray Optics and Optical Instruments.
Kerala Plus Two Physics Chapter Wise Previous Questions and Answers Chapter 9 Ray Optics and Optical Instruments
Two thin convex lenses of focal length f1 and f2 are placed in contact:
a. If the object is at principal axis, draw ray diagram of the image formation by this combination of lenses.
b. Obtain a general expression for effective focal length of the combination in terms of f1 and f2.
A ray of light through a prism. If the refracted ray QR is parallel to the base BC, as shown in figure.
a. Derive an expression to find out deviation (d) .
b. Draw a graph which shows the variation of ‘d’ with ‘i’.
c. Calculate the angle of minimum deviation if A = 60° and refractive index of the material of prism is 1.62.
A concave lens always produces …………….images [March-2017]
iv. None of these
a. Speed of light in glass is 2 × 108 m/s. Refractive index of glass is_______
b. For an equilateral prism made of a material of refractive index , find the angle of minimum deviation for a ray of monochromatic light,
c. Draw the ray diagram of a simple microscope that uses a single convex lens. Derive an expression for its linear magnification. [March-2017]
c. A simple magnifier or microscope is a converging lens of small focal length. In order to use such a lens as a microscope, the lens is held near the object, one focal length away or less, and the eye is positioned close to the lens on the other side. The idea is to get an erect, magnified and virtual image of the object at a distance so that it can be viewed comfortably, i.e., at 25 cm or more.
If the object is at a distance f, the image is at infinity. However, if the object is at a distance slightly less than the focal length of the lens, the image is virtual and closer than infinity. Although the closest comfortable distance for viewing the image is when it is at the near point (distance D = 25 cm), it causes some strain on the eye. Therefore, the image formed at infinity is often considered most suitable for viewing by the relaxed eye. We show both cases, the first in Fig. (1), and the second in Fig. (2) and (3). The linear magnification m, for the image formed at the near point D, by a simple microscope can be obtained by using the relation.
Now according to our sign convention, v is negative, and is equal in magnitude to D. Thus,the magnification is
The following is a choice question:
a. If the focal length of a double convex lens is 12 cm and radii of curvature of faces are 10 cm and 15 cm respectively, what is the refractive index of the lens?
b. i. Draw the ray diagram showing the formation of image by a compound microscope.
ii. Show that in order to achieve large magnification in a compound microscope the magnitude of focal length of objective and eye piece should be small. [March-2016]
a. What is the structure of an optical fibre ?
b. What is the principle used for transmitting audio and video signals using optical fibre ? Explain the principle.
It is a device based on the principle of TIR. It can transmit light signals from one point to another with very little loss of intensity. It consists of a core and a cladding. The cladding has lower refractive index than the core.
b. Total internal reflection is the phenomenon behind the transmission of audio and video signals through optical fibres. When light travels from an optically denser medium to a rarer medium at the interface, it is partly reflected back into the same medium and partly refracted to the second medium. This reflection is called the internal reflection.
i. A convex lens
a. is thicker at the edges than at the middle.
b. is thicker at the middle than at the edges.
c. diverges rays of light.
d. is of unifom thickness everywhere.
ii. With the help of a ray diagram sketch the image formation of a convex lens when the object is between C and F.
iii. Derive the lens maker’s formula. [March-2015]
i. b. is thicker at the middle than at the edges.
i. A ray of light travels from a denser to a rarer medium then, the ray
a. does’nt bend at all.
b. bends towards the normal.
c. bends away from the normal.
d. goes along the normal.
ii. Draw a diagram showing the path of a monochromatic light through a triangular prism.
iii. Using this diagram obtain the relation [March]
i. c. bends away from the normal
Light has several properties like reflection, refraction etc. When light travels from an optically denser medium to a rarer medium?
a. What happens to the light at the interface?
b. Give a demonstration for total internal reflection.
c. What are the technological applications of total internal reflection in nature? Briefly explain it.
d. What is the Brewster angle for air to glass transition? (Refractive index of glass is 1.5)
a. Describe Young’s experiment in interference with necessary theory.
b. Explain the refraction at a spherical surface using a schematic diagram.
c. Mention the shape of wave front for the portion of wave front of light from a distant star intercepted by the earth. [March-2014]
a. The light ray undergoes refraction.
1. Brightness of Diamond
2. Optic fibre
d. tan θn ; where θ – angle of polarising / Brewster angle, n – refraction index of that medium
tan θ = 0 = tan-1 (3/2)
a. The experiment consist of a slit ‘S’. A monochromatic light eliminates the slit S1 and S2 are 2 other slits placed infront of the slit S’ as shown in the fig. 4 screen placed at a suitable distance from S1 & S2 on the screen interferance pattern can be seen.
b. O- object, OA- incident ray, R- is the radius of the spherical surface, i – angle of incidence, r – angle of refraction, I – Image formed i
A lens of required focal length is made from a glass slab of refractive index n by adjusting its radius of curvature.
a. Define refractive index of a medium.
b. Derive lens makers formula using the expression for refraction at a spherical surface.
c. The focal length of a convex lens in air is 20cm. Find its focal length when it is immersed in water of refractive index 1.33 (Refractive index of the material of the lens is
In order to produce much larger magnification, we use compound microscope.
a. What do you meant by magnification produced by an optical instrument?
b. Draw the schematic diagram of the formation of image in a compound microscope.
c. Derive the expression to magnification produced by the compound microscope in terms of length of microscope and least distance of distinct vision when the final image is formed at least distance of distinct vision.
a. Refractive index is the ratio of the sin . of the angle of incidence to the sin of the angle of refraction.
we know that
c. For a glass lens in air,n2= 1.5, n1= 1, f = +20 cm ,
The lens formula,
a. Magnification of an optical instrument is the ratio of image distance to the object disturbance ,i.e ,m=v/u
i. An equilateral glass prism is placed on a horizontal surface. A ray PQ is incident on it. For minimum deviation
a. PQ is horizontal
b. QR is horizontal
c. RS is horizontal
d. None of these
ii. A thick lens gives coloured images due to………….
iii. ln a compound microscope the nature of the intermediate image is …………..
iv. Based on refraction and total internal reflection explain the formation of rainbow. [March-2013]
i. QR is horizontal.
iii. Real, inverted and magnified.
iv. In a primary rainbow, after refraction at the surface of water droplet, the ray suffers one internal reflection and finally comes out of the drop by forming an inverted spectrum. The maximum deviated light is red (42°) and the least deviated light is violet (40°).
In a secondary rainbow, after refraction at the surface of water droplet, the ray suffers two internal reflection and finally comes out of the droplet by forming a spectrum. The most deviated light is violet (53°) and the least deviated light is red (50°).
A spherical surface of radius of curvature R, separates a rarer and a denser medium as shown in the fig.
a. Complete the path or the incident ray of light, showing the formation of a real image. [March-2012]
b. Derive the relation connecting object distance u, image distance v, radius of curvature R and refractive indices n1 and n2 of the two media.
c. A thin convex lens of focal length 5 cm is used as a simple microscope by a person with normal near point (25 cm). What is the magnifying power of the microscope?
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