5-Lenses
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Port Said International Schools Better Education for Future Generations Science Department Grade: 9 5-Lenses Name: ………………………………………. Date: …………………………………………………… Complete the following statements: 1. The most important vision defects are ………….. and ……………. 2. The convex lens ……………. light, while the convex mirror …………….. light. 3. The image formed by a concave lens is always ……………, …………….., and …………………. 4. The radius of curvature of a concave lens = …………….. its focal length. 5. The image formed by …………………. is always virtual, erect and diminished. 6. The person who suffers from short-sightedness is treated by using …………….. 7. The incident light ray falls parallel to the principle axis of a convex lens penetrates the lens passing by …………………… 8. ……………… and …………….. are types of mirrors. 9. The image formed by a concave lens is characterized by ………………, ………………….. and ………………..when an object lies in front of a …………… lens a virtual diminished image is formed. 10.When an object lies in front of a concave mirror at a distance ……...………………. from its focal length a real, smaller and ………………… image is formed. 11. The concave lens ……………….. the rays fallen on it. 12.The ……………….. lens that is thin at the center and thick at the tips …………….. the light rays. 13.The ……………….. lens that is thick at the center and thin at the tips …………….. the light rays. 14.The focal length of a convex lens equals the distance between ………………. and ……………….. 15.When the focal length of a concave lense = 10 cm, the radius of curvature = ………. 16.When an object is placed between the focus and the center of curvature of a convex lens, the image formed is ………………, ……………….. and ………………… 17. The contact lenses are very ………………that are made of ……………. and can stick to the eye ………………… by the eye fluid. Choose the correct answer: 1. The concave lens is called the (diverging – converging – collecting – no correct answer) lens. 2. The imaginary point in the center of the lens which lies on the principle axis is called (real focus – optical center – secondary axis – center of curvature). 3. The straight line that connects between the center of curvature of the lens and its optical center is called …………………. 4. From the opposite figure, the radius of curvature = (5 cm – 10 cm – 15 cm – 20 cm). 1 Port Said International Schools Better Education for Future Generations Science Department Grade: 9 5-Lenses 5. From the opposite figure, the focal length = (PQ – PS – QR – QS). 6. Which of these figures represents the correct image formed by a convex lens? 7. Which of the following figures represents the correct path of rays through a convex lens? 8. The image that is formed on the retina is (erect – real – enlarged – magnified). Write the scientific term: 1. A transparent medium that refracts the light and it is defined with two spherical surfaces and usually made of glass or plastic. ……………………………………….. 2. A lens that is thick at the center, thin at the tips and it converges light rays. ……………………………………………………………………………………………….. 2 Port Said International Schools Better Education for Future Generations Science Department Grade: 9 5-Lenses 3. A lens that is thin at the center, thick at the tips and it diverges light rays. ………………………………………………………………………………………………. 4. The center of the sphere where the face of the lens is part of it. …………………….. 5. The point inside the lens lies on the principal axis in the mid distance between its faces. ………………………………………………………………………………… 6. Half the radius of the sphere where the face is a part of it. ………………………….. 7. The line between the centers of curvature of the lens passing by the optical center of the lens. ………………………………………………………………………………. 8. A point in which the light rays are collected. ………………………………………… 9. A point in which the reflected and refracted light rays are collected. ………………………………………………………………………………………… 10.A point in which the extensions of reflected and refracted light rays are collected. ……………………………………………………………………………………………….. 11.The image that can be received on a screen. ………………………………………… 12.The image that can’t be received on a screen. ……………………………………….. 13.A vision defect in which near objects can be seen clearly and far objects are distorted. ……………………………………………………………………………. 14.A vision defect in which far objects can be seen clearly and near objects are distorted. ……………………………………………………………………………. 15.An optical piece that is used instead of glasses, thin and made of plastic. ……………………………………………………………………………………………….. Give reason(s) for the following: 1. The convex lens is a converging lens. ……………………………………………………………………………………………… ……………………………………………………………………………………………… 2. The concave lens is a diverging lens. ……………………………………………………………………………………………… ……………………………………………………………………………………………… 3. Lenses have two centers of curvature, while mirrors have only one center of curvature. ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… 4. The focus in the convex lens is a real focus. ……………………………………………………………………………………………… ……………………………………………………………………………………………… 5. The focus in the concave lens is a virtual focus. ……………………………………………………………………………………………… ………………………………………………………………………………………………. 3 Port Said International Schools Better Education for Future Generations Science Department Grade: 9 5-Lenses 6. Short-sighted person can see near objects clearly and far objects in distorted a way. ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………….. 7. Long-sighted person can see far objects clearly and near objects in distorted a way. ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… 8. Short-sightedness is treated by using a concave lens. ……………………………………………………………………………………………… ……………………………………………………………………………………………… 9. Long-sightedness is treated by using a convex lens. ……………………………………………………………………………………………… ……………………………………………………………………………………………… 10.The object in front of a convex lens at the focus doesn’t have an image. ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… 11. The convex lens is used in burning papers with the sun rays. ……………………………………………………………………………………………… ……………………………………………………………………………………………….. 12.The image formed by a concave lens can’t be received on a screen. ……………………………………………………………………………………………….. Show by drawing the image and its properties when needed in the following cases: (Use a separate paper sheet): 1. Short-sightedness. 2. Treatment of short-sightedness. 3. When an object is put in front of a concave lens. 4. When an object is in front of a convex lens at distance less than double the focal length and bigger than the focal length. 4 Port Said International Schools Better Education for Future Generations Science Department Complete the following comparisons: Point of comparisons Concave mirror Definition Grade: 9 5-Lenses Convex mirror Shape Properties if image Points of comparisons Type of mirror Concave mirror Plane mirror Properties of image Real image Points of comparisons Definition Reasons Treatment 5 Virtual image Long-sightedness Short-sightedness Port Said International Schools Better Education for Future Generations Science Department 6 Grade: 9 5-Lenses
