Case Study Questions Class 10 Science Chapter 10 Light Reflection and Refraction
CBSE Class 10 Case Study Questions Science Light Reflection and Refraction. Important Case Study Questions for Class 10 Board Exam Students. Here we have arranged some Important Case Base Questions for students who are searching for Paragraph Based Questions Light Reflection and Refraction.
At Case Study Questions there will given a Paragraph. In where some Important Questions will made on that respective Case Based Study. There will various types of marks will given 1 marks, 2 marks, 3 marks, 4 marks.
Case study:1
We can see when the pencil immersed in water it appears like bent at the water air interface. Also, the letters appears to be raised when we will see that letters through a glass slab placed over it. If the media used are different that means the bending of light is different in different media. And hence we can say that the light does not travel along a straight line path through different media. According to the velocity of light in that medium the bending of light takes place. Thus, we can say the phenomenon in which light ray bends or changes its direction when traveling from one medium to other is called as refraction of light. And also we can observed that if the ray of light is traveling from rarer medium to denser medium it bends towards the normal whereas when the ray of light travels from denser medium to rarer medium it bends away from the normal. And the extent of bending of light in a particular medium depends on the refractive index of the medium mostly. More the refractive index more is the bending or denser is the medium and less will be the velocity of light in that medium.
If less is the refractive index then less will be the bending or medium is rarer and velocity of light will be more in that medium. Like the refractive index of air is found to be 1.0003 and that of water is found to be 1.33. And hence water is more denser than air, air is rarer medium as compared to water. Thus, velocity of light in air medium is greater than velocity of light in water medium.
The absolute refractive index of the medium is given by
Absolute Refractive index= (speed of light in air)/(speed of light in medium) = c/v
Thus, for different media refractive index is different and accordingly the velocity of light is also different.
1) If the refractive indices of glass and ice are 1.52 and 1.31 respectively. Then in which medium the velocity of light is more? What it’s value?
( Velocity of light in air= 3*108 m/s)
2) How you can define rarer and denser medium on the basis of optical density?
3) If the Refractive index of diamond is found to be highest i.e. 2.42 then what it indicates?
4) What will happen if we took a glass filled with kerosene instead of water? What would be the observations?
Case study: 2
We have, the object distance is the distance of the object from the pole of the mirror. And we always know that object is placed in front of mirror that means on left side and hence object distance u is always taken as negative. The distance of the image from the pole of the mirror is taken as image distance. The image distance may be positive or negative on the basis of nature of image formed. And the distance of principal focus from the pole is called as focal length of the mirror. Thus, the relationship between the object distance u, image distance v and focal length f is given by mirror formula.
Thus,
Mirror formula:
1/v + 1/u = 1/f
And magnification in case of mirror gives the extent to which the image is magnified as compared to object size. Magnification is given by the ratio of height of image (h’) to the height of object (h).
Thus, magnification = (height of image)/(height of object)
Thus, m = h’/h
Also, in terms of object distance and image distance magnification is given by,
Magnification m = h’/h = -v/u
As we know that, image height is positive if the image formed is virtual while height of image is negative for real images.
Similarly in case of lenses, lens formula is given by
1/v – 1/u = 1/f
And magnification in case of lenses is given by
Magnification m = h’/h = v/u
The power of lens depends on the focal length of the lens and it is the ability of the lens to diverge or converge the number of rays incident on it. Also, power of lens is defined as the reciprocal of focal length of the lens.
Thus, P = 1/f
Questions:
1) If the focal length of the lens is measured in meter what will be the unit of power of lens?
2) What is the sign of power of convex and concave lens?
3) If the lenses placed in contact of powers P1, P2, P3, P4 are used then what is the net power of lens system?
4) If the magnification produced is negative and positive in case of mirrors then what about the nature of images formed there?
Answers:
1) If the focal length of the lens is used in meter then the power of the lens is measured in dioptre or D or m-1.
2) As the focal length of convex lens is positive and hence the power of convex lens is positive.
Also, as the focal length of concave lens is negative and hence the power of concave lens is negative.
3) If in a lens system four lenses of power P1, P2, P3 and P4 are in contact then net power of lens system is the algebraic sum of given power of lenses.
P= P1 + P2 + P3 + P4
4) If the magnification produced is negative then the image formed is real. And if the magnification produced is positive then the image formed is virtual.
Case study:3
As we know that, in case of concave mirrors when a ray of light parallel to principal axis strikes the mirror and after reflection it passes through principal focus of the concave mirror. Also, a ray which is passing through the principal focus of the concave mirror after reflection goes parallel to the principal axis. And the ray of light which is passing through the centre of curvature of concave mirror after reflection retraces the same path in backward direction. Because of converging property of concave mirrors they are used in solar furnaces to concentrate more light to produce huge amount of heat energy. They are also used in search lights, torches, head lights of vehicles so that a strong parallel beam of light will be produced. Also, in case of shaving mirrors concave mirrors are used to see larger face of the person.
While convex mirrors are used as rear view mirror in vehicles to see the traffic behind the person for safe driving. As these mirrors are curved outwards they has wider field of view. In convex mirrors the image formed is always diminished, virtual and erect.
In concave mirror, when the object is at infinity the image formed will be at focus F and which is highly diminished, point sized, real and inverted.
Questions:
1) In case of concave mirror when the image formed is virtual and erect?
2) In which case the image formed is of same size as the object in case of concave mirrors?
3) Which mirrors are called as converging and diverging mirror?
4) The focal length of concave mirror is______ and the focal length of convex mirror is _______.
Answers:
1) In case of concave mirrors, when the object is placed between pole P and focus F of the mirror then the image formed is behind the mirror which is enlarged, virtual and erect.
2) When the object is placed at centre of curvature C of the mirror then image formed is also at centre of curvature C which is of same size, real and inverted.
3) Concave mirror is called as converging mirror while convex mirror is called as diverging mirror.
4) The focal length of concave mirror is positive and the focal length of convex mirror is negative.
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Answer for the 4th question of the last case study is wrong
It is +ve for convex mirror and -ve for concave mirror
Where is the case 1 answer