How will it emerge after refraction through the lens? Convex lens produces an image of same size as that of object. Question 4. Convex Lens Practical Class 10 Introduction. Question 11. 10. (a) decrease (b) at 2F You will generally find inverted and real images. (a) +u, + v, +f Image formation by convex lens ray diagrams. The focal length of the lens will change thereby affecting the position of the image formed. [NCERT] Answer: If the lens is thick and having larger aperture, then it will not form image at the given location. Question 5: What is a lens? Answer: Types of Images There are two types of images : Formation of Image by a Convex Lens The table given below illustrates the ray diagrams alongwith the position and nature of image, formed by convex lens for various positions of the object. Question 6: (b) – u, -f, + v Theory/Principle The position, nature and size of the images of an object formed by a thin convex lens, depends on the position of the object and can be studied using new Cartesian sign convention and drawing ray diagrams. Answer: Incident rays parallel to the principal axis on passing through convex lens meet at The three types of lens are double convex lens, plano-convex and concavo-convex lens. (b) increase Question 3: Answer: (d) f = 20 cm, then 2f= 40 cm, the object at 2F gives the image at 2F. Define power of a lens. 3. A convex lens. Question 15: (b) concave lens which is diverging in nature The size of the image is much smaller than that of the object. The centre of lens, centre of stand of candle flame and centre of screen, may not be in same straight line and parallel to measuring scale. (a) concave lens (d) none of these, 29. Between F and 2F 5. Question 1: A straight ray of light passing through the centre of a lens and centre of curvatures is called principal axis. (c) 100 cm A ray of light is passing through the principal focus of a convex lens. Note down the position of screen, s. Find the distance y and record the height h’ of image of candle flame obtained on the screen. When an object is placed at infinity, the real image is formed at the focus. In each case he measured the distance of the image from the lens. Mount a small candle in a centred mark stand vertically and light it. [NCERT] Answer: When a light ray passes through principal focus after refraction, it will be parallel to the principal axis. Result The image distances for varying object distances in case of convex lens is given below: PrecautionsIt is clearly visible from the above table as the object is movqd from infinity towards the optical centre of thin convex lens, the image distance increases gradually and height of image also increases gradually. If the distance between the object and it's image In physics,what kind of image will be form when concave and convex mirror and in lens are kept together Is there any ratio for size of object in Convex mirror and real size of object ? Mark a point ‘F’ at both the sides of the lens as focus of the lens by knowing the focal length as calculated in first step. Also, measure and record the height h’ of the image of the candle flame obtained on the screen. Now, shift the object between F and 2F and record the observations. Answer: Laws of refraction of light are obeyed by light rays when refracted through a convex lens. (c) principal axis For thick convex lens with larger aperture does not show the image of same size. What is meant by principal axis of a lens? (d) all of these, 3. A convex lens has focal length of 20 cm. Question 4. (b) concave lens Question 8. Will virtual image formed by convex lens be erect or inverted? THEORY: A thin convex lens can be characterized by its focal length f, the object distance, d o and the image distance, d i Answer: Find the distance, x (say) between the optical centre O of the lens and candle flame (object). (a) at F (c) – u, – v, -f 2. NCERT Class 10 Science Lab Manual – Image Formation by a Convex Lens Practical. Power of lens is defined as the reciprocal of its focal length in metre. The experiment may not be performed in a dark room. Why do we require a calm atmosphere to perform this experiment? (d) more than focal length, 14. To obtain real and enlarged image we will use convex lens and place the object between F and 2F. Draw a thin line of about 15-18 cm length in the middle of the white sheet. (c) at 10 cm It is the distance between the optical centre and its principal focus. (a) real, erect, magnified Question 10: (a) no image is Question 4: Convex lens is called converging lens because it converges the parallel beam of light passing through it at a point. At the focus F 6. (c) Rays coming from beyond F meet after refraction. When the object is placed between focus of the lens and the aperture of the lens then the image formed will be magnified and lens can be used as magnifying lens. The ray passing through optical centre passes straight through the lens and remains undeviated. As you bring the object more close to the lens, we get the image all the more enlarged. [NCERT] Answer: Thick convex lens has shorter focal length so image distance will be reduced as compared to thin lens. Question 7. (b) aperture CBSE Class 10 Science Lab Manual – Image Formation by a Convex Lens. Which laws of light are obeyed by the light rays when refracted through a convex lens? Question 9: Answer: A virtual, erect and magnified image will be formed. 30. A student did an experiment with a convex lens. (b) beyond centre of curvature Convex lens is used as a magnifying glass. (c) Distances measured in the direction of the incident rays are positive and the distances measured in the direction opposite to that of the incident rays are negative. Question 4: For obtaining distinct and sharp images of candle flame, perform this experiment in a dark room. A ray of light passing through optical centre does not deviate. The formation of images by a convex lens can be studied by drawing ray diagrams and by following New Cartesian sign convention. Answer: If we do not draw an equiconvex lens, then the condition OF1 = OF2 will not hold good and the image obtained will not be accurate. Answer: The student found that to obtain a sharp image he has to move the lens away from the screen. (d) between F and 2F, 13. (d) none of these. If the image formed by the given lens is inverted then it is convex lens otherwise it is a concave lens. The convex lens generally produces the image of the object placed at 2F1 of same size at 2F2 as that of the object. What effect do you expect if the lens used to perform the experiment has scratches on it? 12. (a) concave And in case if object is placed between F and O, it will be virtual and erect. (b) real and inverted Question 3.