Description : Two thin lenses of power `+ 3 D and - 1 D` are held contact with each other. Focal length of the combination is :
Last Answer : Two thin lenses of power `+ 3 D and - 1 D` are held contact with each other. Focal length of the combination is :
Description : In the following diagram are shown the position of an object O, image I and two lenses. The focal length of one lens is also given. Determine the foca
Last Answer : In the following diagram are shown the position of an object O, image I and two lenses. The ... given. Determine the focal length of the other lens.
Description : In the following ray diagram are given the position of an object O, image I and two lenses `L_(1)` and `L_(2)`. The focal length of `L_(1)` is also gi
Last Answer : In the following ray diagram are given the position of an object O, image I and two lenses `L_(1)` ... also given. Find the focal length of `L_(2)`.
Description : Pick up the correct specification of Ramsden eyepiece from the following: (A) It consists of two equal piano convex lenses (B) The curved surfaces of Plano-convex lenses face each other (C) ... from a point on the diaphragm enter the eye as a parallel beam (D) All the above
Last Answer : (D) All the above
Description : Pick up the correct statement from the following: (A) The power of a lens is the reciprocal of its focal length (B) The unit of power of the lens is Diopter (C) The power of two or more thin lenses in contact is the power of the combination of the lenses (D) All the above
Description : Two concave lenses of 60 cm focal length are cemented on either side of a convex lens of 15 cm focal length. The focal length of the combination is (A) 10 cm (B) 20 cm (C) 30 cm (D) 40 cm
Last Answer : (C) 30 cm
Description : Bi-focal Eyeglass wearers, do you use Progressive (No Line) or Line lenses?
Last Answer : Can’t get use to em!! I went back to single vision, much safer too :-/
Description : Anyone out there using Bausch & Lomb Multi-Focal contact lenses?
Last Answer : I don’t use the multi-focal, I don’t think. I use the ones that are two different strengths and allow you to see close up and far away. They simulate bi-focals. If these are multi-focals I like them very much and have worn them for about three years.
Description : Two thin lenses of focal lengths 15 cm and 30 cm resepectively are kept in contact with each other. What is the power of the combined system?
Last Answer : Two thin lenses of focal lengths 15 cm and 30 cm resepectively are kept in contact with each other. What is the power of the combined system?
Description : A compound lens is made of two lenses having powers `+15.5 D` and `-5.5D`. An object of 3cm height is placed at a distance of 30 cm from this compound
Last Answer : A compound lens is made of two lenses having powers `+15.5 D` and `-5.5D`. An object of ... cm from this compound lens. Find the size of the image.
Description : Sumati did some preliminary experiment with the lenses and found out that the magnification of the eyepiece (L 2 ) is 3. If in her experiment with L 2 she found an image at 24 cm from the lens, at what distance did she put the object? (a) 72 cm (b) 12 cm (c) 8 cm (d) 6 cm
Last Answer : (c) 8 cm
Description : R = -0.25 Into 15 Degree L = -0.25 Into 175 Degree Which would be better to use ? Spectacles or contact lenses ?
Last Answer : If you want to use contact lenses, but it is very useful, it is important to take some precautions. Each contact lens has a specific expiration date. It can be 3 months-6 months-1 year. ... cheap quality products that hurt your eyes while keeping an eye on the price. Learn more about other things
Description : A 60-year-old man was diagnosed last year with adenocarcinoma of the lung, and a 4 cm mass lesion was treated with a right lower lobectomy. He now has an ... 2) Membranous glomerulonephritis 3) Minimal change glomerulonephritis 4) Nodular glomerulosclerosis 5) Rapidly progressive glomerulonephritis
Last Answer : Answers-2 Most cases of membranous GN are idiopathic, but in some patients there is a history of an infection or a malignancy (usually lung) with antigenemia.
Description : A concave mirror of focal length 15 cm can form a magnified, erect as well as inverted image of an object placed in front of it." Justify this statement stating the position of the object with respect to the pole of the mirror in both the cases for obtaining the images. -Science
Last Answer : For magnified and erect image the object is placed between pole P and focus F. For magnified and inverted image the object is placed either at focus or anywhere between F and C.
Description : When a person walking in bright sunlight enters a dark room, he is not able to see clearly for a little while because (a) The eye muscles cannot immediately change the focal length of the eye ... iris is unable to contract the pupil immediately (d) The iris is unable to dilate the pupil immediately
Last Answer : Ans:(d)
Description : The power of a convex lens is +2.5. Then its focal length is (a) 20 cm (b) 50 cm (c) 30 cm (d) 40 cm
Description : An object is placed at a distance equal to the focal length of convex mirror. If the focal length of the mirror be f, then the distance of the image from the pole of the mirror is (a) Less than f (b) Equal of f (c) More than f (d) Infinity
Last Answer : Ans:(a)
Description : To increase the magnifying power of telescope, we should increase (a) The focal length of the objective (b) The focal length of the eyepiece (c) Aperture of the objective (d) Aperture of the eyepiece
Description : A concave mirror produces a real, inverted image of the same size of the object. Then, the object is at a distance (a) Less than f from the mirror (b) Equal to f from the mirror (c) Equal to 2f from the mirror (d) Larger than 2F from the mirror where f is the focal length of the mirror
Last Answer : Ans:(c)
Description : An object of height 4 cm is kept at a distance of 80 cm from the pole af a diverging mirror. If the focal length of the mirror is 10 cm. the height of the image formed is (a) + 3.0 cm (b) + 2.5 cm (c) + 1.0 cm (d) + 0.75 cm
Last Answer : (c) + 1.0 cm
Description : A converging lens forms a three times magnified image of an object, which can be take on a screen. If the focal length of the lens is 30 cm, then the distance of the object from the lens is (a) - 55 cm (b) - 50 cm (c) - 45 cm (d) - 40 cm
Last Answer : (d) - 40 cm
Description : Magnifying power of a simple microscope can be increased by ? A. increasing focal length of the lens B. Decreasing focal length of the lens (Answer) C. Lens of large aperture D. lens of short aperture E. None of these
Last Answer : B. Decreasing focal length of the lens (Answer)
Description : The focal length of mirror is (a) -16 cm (b) 12 cm (c) -15 cm (d) 10 cm
Last Answer : (a) -16 cm
Description : If the radius of curvature of concave mirror is 12 cm. Then, the focal length will be : (a) 12 cm (b) 6 cm (c) -24 cm (d) -6 cm
Last Answer : (b) 6 cm
Description : The focal length of the mirror is (a) 0.5 m (b) 1 m (c) 0.78 (c) 1.5 m
Last Answer : (b) 1 m
Description : A student focuses the image of a candle flame, placed at about 2 m from a convex lens of focal length 10 cm, on a screen. After that he moves gradually the flame towards the lens and each time focuses its ... d) What is seen on the screen when the flame is very close (at about 5 cm) to the lens?
Last Answer : (a) The student moves the lens away from the screen to focus the image because on moving the candle towards the lens, the image distance increases. (b)The size of the image increases when the object ... on the screen. A virtual image is formed behind the candle on the same side of the screen.
Description : How to turn dioptres into focal length?
Last Answer : You’ve got it right. The dioptres = 1/focal length, so focal length = 1/dioptres. e.g. 3.3 dioptres = 1/(3.3) = 0.30303m focal length -2 dioptres = 1/(-2) = -0.5m focal length http://medical-dictionary.thefreedictionary.com/Dioptres for more info.
Description : Can you explain the difference between a prime/fixed focal length lens and one where the focal length can be varied?
Last Answer : With a zoom lens, you can change the focal length to zoom in or out (there's a proper name for it but it escapes me). With a prime lens, it's fixed - no zoom. Because prime lenses are ... a zoom.. You'd just use them differently and get slightly different results. I think Pros only use prime lenses.
Description : 15. An object 2 cm high is placed at a distance of 64 cm from a white screen. On placing a convex lens at a distance of 32 cm from the object it is found that a distinct image of the object is formed on the screen. What is the focal length of the conve -Chemistry-10
Last Answer : Since, object-screen distance is double of object-lens separation, the object is at a distance of 2f from the lens and the image should be of the same size of the object.
Description : 14. An object 2 cm in size is placed 30 cm in front of a concave mirror of focal length 15 cm. At what distance from the mirror should a screen be placed in order to obtain a sharp image? What will be the nature and the size of the -Chemistry-10
Last Answer : Answer. hope this helps you
Description : 2. An object 50 cm tall is placed on the principal axis of a convex lens. Its 20 cm tall image is formed on the screen placed at a distance of 10 cm from the lens. Calculate the focal length of the lens. [All India] -Chemistry-10
Last Answer : this is the answer for the respected question
Description : 1. A concave lens has focal length of 20 cm. At what distance from the lens a 5 cm tall object be placed so that it forms an image at 15 cm from the lens? Also calculate the size of the image formed. [Delhi] -Chemistry-10
Last Answer : Answer. hope this helps youu
Description : 17. A doctor has prescribed a corrective lens of power +1.5 D. Find the focal length of the lens. Is the prescribed lens diverging or converging? -Physics-10
Last Answer : Power of lens (P) = 1/f P = 1.5D f = 1/1.5 = 10/15 = 0.66 m A convex lens has a positive focal length. Therefore, it is a convex lens or a converging lens.
Description : 16. Find the focal length of a lens of power -2.0 D. What type of lens is this? -Physics-10
Last Answer : Power of lens (P) = 1/f P = -2D f = -1/2 = -0.5 m A concave lens has a negative focal length. Therefore, it is a concave lens.
Description : 15. An object of size 7.0 cm is placed at 27 cm in front of a concave mirror of focal length 18 cm. At what distance from the mirror should a screen be placed so that a sharply focused image can be obtained? Find the size and nature of the image. -Physics-10
Last Answer : Object distance (u) = – 27 cm Object height (h) = 7 cm Focal length (f) = – 18 cm According to the mirror formula, The negative value of image height indicates that the image formed is inverted.
Description : 12. An object is placed at a distance of 10 cm from a convex mirror of focal length 15 cm. Find the position and nature of the image. -Physics-10
Last Answer : Focal length of convex mirror (f) = +15 cm Object distance (u) = - 10 cm According to the mirror formula, The image is located at a distance of 6 cm from the mirror on the other ... and a value of less than 1 of magnification indicates that the image formed is virtual and erect and diminished.
Description : 11. A concave lens of focal length 15 cm forms an image 10 cm from the lens. How far is the object placed from the lens? Draw the ray diagram. -Physics-10
Last Answer : Focal length of concave lens (OF1), f = – 15 cm Image distance, v= – 10 cm According to the lens formula, The negative value of u indicates that the object is placed 30 cm in front of the lens. This is shown in the following ray diagram.
Description : 10. An object 5 cm in length is held 25 cm away from a converging lens of focal length 10 cm. Draw the ray diagram and find the position, size and the nature of the image formed. -Physics-10
Last Answer : Height of the Object, h0 = 5 cm Distance of the object from converging lens, u = -25 cm Focal length of a converging lens, f = 10 cm Using lens formula, Thus, the image is inverted and formed at a distance of 16.7 cm behind the lens and measures 3.3 cm. The ray diagram is shown below.
Description : We wish to obtain an erect image of an object, using a concave mirror of focal length 15 cm. What should be the range of distance of the object from the mirror? -Physics-10
Last Answer : Range of the distance of the object = 0 to 15 cm from the pole of the mirror. Nature of the image = virtual, erect, and larger than the object.
Description : 4. A spherical mirror and a thin spherical lens have a focal length of -15 cm. The mirror and the lens are likely to be -Physics-10
Last Answer : (a) Both are likely to be concave.
Description : 3. Find the power of a concave lens of focal length 2 m. -Physics-10
Last Answer : Focal length of concave lens (f) = 2 m Power of lens (P) = 1/f = 1/ (-2) = -0.5D
Description : 1. Find the focal length of a convex mirror whose radius of curvature is 32 cm. -Physics-10
Last Answer : Radius of curvature (R) = 32 cm Radius of curvature = 2 × Focal length (f) R= 2f f = R/2 = 32/2 = 16 Therefore, the focal length of the given convex mirror is 16 cm.
Description : 2. The radius of curvature of a spherical mirror is 20 cm. What is its focal length? -Physics-10
Last Answer : Radius of curvature (R) = 20 cm Radius of curvature of the spherical mirror = 2 × Focal length (f) R = 2f f= R/2 = 20 / 2 = 10 Therefore, the focal length of the spherical mirror is 10 cm.
Description : A convex lens has a focal length of 10 cm. At what distance from the lens should the object be placed so that it forms a real and inverted image 20 cm away from the lens? What would be the size of ... ? With the help of a ray diagram show the formation of the image by the lens in this case. -Physics
Last Answer : This is the Answe:
Description : An object 2 cm high is placed at a distance of 64 cm from a white screen. On placing a convex lens at a distance of 32 cm from the object it is found that a distinct image of the object ... diagram to show the formation of the image in this position of the object with respect to the lens. -Physics
Description : An object 50 cm tall is placed on the principal axis of a convex lens. Its 20 cm tall image is formed on the screen placed at a distance of 10 cm from the lens. Calculate the focal length of the lens. -Physics
Last Answer : The focal length' of convex length is 7.14 cm. Solution: The given quantities are Height of the object h = 50 cm Height of the image formed h' = -20 cm Image distance v = 10 cm The image ... object distance will be So the focal length will be Thus the focal length of the convex lens is 7.14 cm
Description : A concave lens has focal length of 20 cm. At what distance from the lens a 5 cm tall object be placed so that it forms an image at 15 cm from the lens? Also calculate the size of the image formed. -Physics
Last Answer : Answer. I hope it helped you.
Description : Which is a part of the eye that helps in changing the focal length of crystalline lensis? -Do You Know?
Last Answer : answer:
Description : The focal length of the lens in a photographic camera is 5 cm. What is the power of the lens? -Do You Know?
Last Answer : P=100/f (in cms) =100/5 1m= 100cm 0.2m= 20cm Hence,the power is 0.2 D The lens is convex as it is positive
Description : The focal length of a convex lens is 50 cm. what is its power? -Do You Know?
Last Answer : convex ( so focal length is positive ) given : f = 50cm or +50×10^-2m so find p =? formula p =1/f p = 1/50×10^-2 p= 100/50 P = 2