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CBSE - XII Science - Physics - Ray Optics and Optical Instruments
Why don't we use sign convention while deriving lens makers formula?
Asked by santhoshsindoora
27th September 2023,
8:26 PM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
obtain the lens formula in case of concave lens
Asked by marvellouskyndiah
17th May 2023,
8:07 AM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
define lens maker formula
Asked by bmahalik21
4th March 2023,
7:03 PM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
sole
Asked by hanskaraja
5th August 2022,
11:20 PM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
if for a perfectly symmertical lens, r1=r2, then how will we find focal length??
Asked by Dark
5th January 2022,
11:54 AM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
Is convex always coverging or it depends on the conditions like refractive indices
Asked by nagendramanikireddy999999
29th May 2021,
11:50 AM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
a person can see up to 1m the nature n power of which will enable him tosee things at 3m
Asked by manjulamurali1979
19th May 2020,
9:01 PM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
ifany body dare tell this sum answer and post it.
Asked by tyeswanthkumar37
14th May 2020,
10:58 AM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
Derive lens formula for concave lens and state lens formula.
Asked by polyrelation
15th March 2019,
4:40 PM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
Derive lens formula for concave lens and state lens formula.
Asked by polyrelation
15th March 2019,
4:40 PM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
An equiconex lens of power p is cut into two equal halves by a plane perpendicular to its principal axis . The power of its halves will be ?
Asked by pradeepjsme
30th January 2019,
3:49 PM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
please solve the question in the picture.
Asked by rohitraman1115
12th January 2019,
12:19 PM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
WHAT IS THE RAY DIAGRAM OF CONCAVE LENS WHEN OBJECT IS PLACED AT FOCUS?
PLEASE EXPLAIN IN DETAIL
Asked by modi72879
7th November 2017,
9:42 AM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
WHAT IS THE RAY DIAGRAM OF CONCAVE LENS WHEN OBJECT IS PLACED AT INFINITY?
PLEASE EXPLAIN IN DETAIL
Asked by modi72879
7th November 2017,
9:41 AM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
Ans with explanation
Asked by Varsneya Srinivas
20th October 2017,
8:42 PM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
If the image formed in cinema is real then shouldn't it be inverted, and how do they avoid it?
Asked by nileshpatel19752000
13th October 2017,
11:52 PM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
Find power
Asked by bijuaylara111
8th September 2017,
12:15 AM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
what is the power and focal length of sunglasses?
Asked by vasturushi
7th September 2017,
10:42 AM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
How do we determine with which type of lens our spectacles are made?
According to the type of eye disordres how do the spectacle makers design them?
Asked by pksunilnair
26th April 2017,
10:22 AM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
briefly explain mathematically how the focal length of a concave lens will change when it is cut
a) vertically at the middle
b) horizontally at the middle
Asked by ppratim02
12th July 2016,
4:56 PM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
briefly explain mathematically how the focal length of a convex lens will change when it is cut vertically at the middle
Asked by ppratim02
12th July 2016,
4:54 PM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
An equiconvex lens is cut into two identical plano convex lens. What is the ratio of focal lengths of equiconvex lens to that of plano convex lens...?
Asked by nayonikamenon15
11th January 2016,
12:33 AM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
draw a ray diagram to show the image formation in refraccting type astronomical telescope in the normal adjusment when image is formed at infinity.derive an expression the aperture of objective lens and why?
Asked by mahamood.iphone
14th December 2015,
9:53 PM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
what will be the focal lenght of the lens if radii of curvature of two surfaces were equal in magnitude and also had the same sign?
Asked by Jahanvi
8th October 2015,
7:41 PM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
What is the relation between focal length and radius of curvature of a lens?Do the two focal lenghs of a lens always have the same value?Are the focal lengths of a lens different for different medium?
Asked by joykphukan
21st July 2015,
9:13 PM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
The focal length of an equiconvex lens is equal to the radius of curvature of either face. What is the refractive index of the material of the lens?
Asked by Topperlearning User
8th July 2015,
11:31 AM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
Q.56 The figure shows a convergent lens placed inside a cell filled with a liquid. The lens has a focal length +20 cm, when in air and its material has refractive index 1.5. if the liquid has a refractive index 1.6, the focal length of the system is
a) +80 cm
b) –80 cm
c) –24 cm
d) –160 cm
Asked by Malavika Umesh
5th May 2015,
6:16 PM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
Young’s double slit experiment is conducted with light of wavelength λ. The intensity of the bright fringe is I. The intensity at point where the path difference is 3λ/4 is given by
a) a]Zero
b) b] I/4
c) c] I/8
d) d] I/2
I cannot solve such type of questions based on calculation of intensity change, final intensity, and initial intensity, in young’s experiment, fraunhofer’s diffraction experiment and polarization experiment. Please guide me I am preparing for MH-CET 2015 which will be held on 7th May
please reply fast So that I can solve these questions myself.
Young’s double slit experiment is conducted with light of wavelength λ. The intensity of the bright fringe is I. The intensity at point where the path difference is 3λ/4 is given by
a) a]Zero
b) b] I/4
c) c] I/8
d) d] I/2
I cannot solve such type of questions based on calculation of intensity change, final intensity, and initial intensity, in young’s experiment, fraunhofer’s diffraction experiment and polarization experiment. Please guide me I am preparing for MH-CET 2015 which will be held on 7th May
please reply fast So that I can solve these questions myself.
Asked by shubham.padamwar.3
5th May 2015,
2:00 PM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
an object is placed 12cm to the left of a converging lens of focal length 8cm.Another converging lens of 6cm focal length is placed at a distance of 30cm to the right of the first lens.Th e second lens will produce
a)no image
b)a virtual enlarged image
c)a real enlarged image
d)a real inverted image
Asked by Malavika Umesh
29th April 2015,
12:14 PM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
A thin plano-convex lens acts like a concave mirror of focal length 0.2m when silvered from its plane surface.THe refractive index of the material of the lens is 1.5. What will be The radius of curvature of the convex surface of the lens??
Asked by Malavika Umesh
26th April 2015,
10:46 PM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
Q.On a convex lens ,light of red and violet colour is incident separately , then how does the focal length of lens change?
Asked by Ravi consul
4th March 2015,
6:48 PM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
A convex lens of focal length 20cm and made of glass of refractive index 1.5 is immersed in water of reffractive index 1.33 calculate change in focal length of the lens
Asked by Sandeep Yadav
6th December 2014,
11:09 PM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
Calculate the distance d show that areal imageof an object at O 15cm is front of a convex lens of focal length 10cm we formed at asame point othe radius of curvature of the mirror is 20cmwill the image inverted and erect .
Asked by Sandeep Yadav
4th December 2014,
8:47 AM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
A concave lens of glass, refractive index 1.5, has both surface of the same radius of curvature R. On immersion in a medium of refractive index 1.75, it will
Asked by yashu.fly
22nd November 2014,
10:18 PM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
1. The focal length of an equiconvex lens in air is equal to either of its radii of curvature. the refractive index of the material of lens is __________
2. A charge of 4x10^-8C is uniformly distributed over the surface of sphere radius 1cm. another hollow sphere of radius 5cm is concentric with the small sphere. find intensity of electric field at a distance 2cm from centre. [K=9x10^9 MKS] [ans in NC^-1]
3. A light of 4560angstrom and 1mW is made incident on photosensitive surface of Cs. If efficiency of surface is 0.1%, then photoelectric current produces is___________
4.A spherical drop of water has 3x10^-10C charge on its surface. 300 volt electric potential exists on its surface. if 27 such identical drops are combined to form a single drop, calculate electric potential on the surface of new drop._____________
Asked by Dhriti
24th October 2014,
12:10 PM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
1. The focal length of an equiconvex lens in air is equal to either of its radii of curvature. the refractive index of the material of lens is __________
2. A charge of 4x10^-8C is uniformly distributed over the surface of sphere radius 1cm. another hollow sphere of radius 5cm is concentric with the small sphere. find intensity of electric field at a distance 2cm from centre. [K=9x10^9 MKS] [ans in NC^-1]
3. A light of 4560angstrom and 1mW is made incident on photosensitive surface of Cs. If efficiency of surface is 0.1%, then photoelectric current produces is___________
4.A spherical drop of water has 3x10^-10C charge on its surface. 300 volt electric potential exists on its surface. if 27 such identical drops are combined to form a single drop, calculate electric potential on the surface of new drop._____________
Asked by Dhriti
24th October 2014,
12:10 PM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
can u plzz explain the difference of sign conventions in the cases of reflection and refraction in both concave and convex lense as well as mirrors also diffrence of sign convention in case of magnfication. it is not clear to through notes .kindly answer this question as quikly as possible ..........
Asked by NAVYA SOOD
19th July 2014,
8:57 PM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
Draw a ray diagram to show the formation of real image of the same size as that of the object placed in front of a converging lens. Using this ray diagram establish the relation between u, v and f for this lens.
OR
Derive the lens formula 
for a concave lens, using the necessary ray diagram.
for a concave lens, using the necessary ray diagram.
Asked by Topperlearning User
8th July 2014,
1:39 PM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
There are n number of lenses of focal length f 1 , f 2 ,....fn in contact. What is the focal length and the power of the combination.
Asked by Topperlearning User
10th June 2014,
9:48 AM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
A convex lens has a focal length of 30cm. An object is placed at a distance of 20cm from the lens. What is the nature of image formed by refraction at lens?
Asked by Topperlearning User
10th June 2014,
9:45 AM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
A convex lens 
behaves as converging lens when dipped in water 
whereas it behaves as diverging lens when dipped in carbon disulphide 
. Why?
behaves as converging lens when dipped in water whereas it behaves as diverging lens when dipped in carbon disulphide . Why?
Asked by Topperlearning User
10th June 2014,
9:28 AM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
Glass of refractive index 1.55 is used to manufacture a double convex lens with the same radii of curvature R. For the focal length of lens to be 25 cm, what is the radius of curvature?
Asked by Topperlearning User
10th June 2014,
9:16 AM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
A pin placed 40 cm from a lens forms an image on a screen placed at 80 cm on the other side of the lens. Determine the type of lens, focal length of lens.
Asked by Topperlearning User
10th June 2014,
8:58 AM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
There is a convex air bubble in a tank of water. State its behavior as a lens.
Asked by Topperlearning User
10th June 2014,
8:55 AM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
Two lenses of power 10 D and -5 D are placed in contact. (i) Calculate the power of lens combination. (ii) Where should an object be held from the lens, so as to obtain a virtual image of magnification 2 ?
Asked by Topperlearning User
10th June 2014,
7:52 AM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
The image of an object formed by a lens on the screen is not in sharp focus. Suggest a method to get clear focussing of the image on the screen without disturbing the position of the object, the lens or the screen.
Asked by Topperlearning User
10th June 2014,
7:20 AM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
A convex lens of refractive index 1.5 has a focal length of 18 cm in air. Calculate the change in its focal length when it is immersed in water of refractive index .
Asked by Topperlearning User
4th June 2014,
1:23 PM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
A convex lens made up of glass of refractive index 1.5 is dipped, in turn, in: (i) Medium A of refractive index 1.65 (ii) Medium B of refractive index 1.33 Explain, giving reasons, whether it will behave as a converging lens or a diverging lens in each of these two media.
Asked by Topperlearning User
4th June 2014,
1:23 PM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
A convex lens of focal length 30 cm is placed coaxially in contact with a concave lens of focal length 40 cm. Determine the power of the combination. Will the system be converging or diverging in nature?
Asked by Topperlearning User
4th June 2014,
1:23 PM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
The radii of curvature of the faces of a double convex lens are 10 cm and 15 cm. If focal length of the lens is 12 cm, find the refractive index of the material of the lens.
Asked by Topperlearning User
4th June 2014,
1:23 PM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
Violet light is incident on a thin convex lens. If this light is replaced by red light , explain with reason, how the power of the lens would change ?
Asked by Topperlearning User
4th June 2014,
1:23 PM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
A figure divided into squares, each of size 1mm2, is being viewed at a distance of 9 cm through a magnifying lens of focal length 10 cm, held close to the eye. (a) Draw a ray diagram showing the formation of the image. (b) what is the magnification produced by the lens ? How much is the area of each square in the virtual image? (c) What is the angular magnification of the lens ?
Asked by Topperlearning User
4th June 2014,
1:23 PM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
Two thin lenses of focal length 5 cm and 10 cm are placed in contact. What will be the focal length of the combination?
Asked by Topperlearning User
4th June 2014,
1:23 PM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
A combination of two thin lenses has a power of +10D. If one of the concave lens has a focal length 1/4m. Find the nature and power of other lens.
Asked by Topperlearning User
4th June 2014,
1:23 PM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
The power of a lens is (i) +6D and (ii) -2D what is the focal length and nature of lens?
Asked by Topperlearning User
4th June 2014,
1:23 PM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
A lens has a focal length of -30cm. What is the nature and power of the lens?
Asked by Topperlearning User
4th June 2014,
1:23 PM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
State the conditions under which the concave lens behave as a converging lens.
Asked by Topperlearning User
4th June 2014,
1:23 PM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
Suppose a lens has different radii of curvature, it forms an image of an object placed on its axis. If we reverse the lens will the position of the image of the object change?
Asked by Topperlearning User
4th June 2014,
1:23 PM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
The refractive index of concave lens is 1.2. This lens is immersed in a liquid of refractive index 1.4. Explain the behavior of the lens.
Asked by Topperlearning User
4th June 2014,
1:23 PM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
The image of a small electric bulb fixed on wall of a room is to be obtained on opposite wall of a room 3m away by means of large convex lens. What is the maximum possible focal length of the lens required for this purpose?
Asked by Sourav Naval
1st June 2014,
1:53 PM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
Write thin lens formula for a convex lens and draw the graph showing the variation of u and v for a convex lens.
Asked by Topperlearning User
22nd May 2014,
3:29 PM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
Calculate the focal length of the combination o f a convex lens of focal length 30 cm in contact with a concave lens of focal length 20 cm. Is the system a converging or a diverging lens ?
Asked by Topperlearning User
22nd May 2014,
2:05 PM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
What is the magnification if n number of lenses are used to magnify an object?
Asked by Topperlearning User
22nd May 2014,
1:25 PM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
What is dioptre?
Asked by Topperlearning User
22nd May 2014,
1:20 PM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
Why do we combine two or more lenses?
Asked by Topperlearning User
22nd May 2014,
1:18 PM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
Focal length of a convex lens is 25cm. Calculate the power of the lens?
Asked by Topperlearning User
22nd May 2014,
12:59 PM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
A +4D glass lens is immersed in water completely. What will be the effect on lens's power?
Asked by Topperlearning User
22nd May 2014,
12:56 PM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
Radius of curvature of a plano-convex lens of glass () is 25 cm. What is the focal length?
Asked by Topperlearning User
22nd May 2014,
9:57 AM
CBSE - XII Science - Physics - Ray Optics and Optical Instruments
explain and derive lens makers formula.
Asked by Sagar krishna
16th May 2014,
6:39 PM
