Leaving Cert. Physics long questions: Geometrical Optics Please remember to photocopy 4 pages onto one sheet by going AY-?+AY and using back to back on the photocopier. 2012 – 2002 Solutions (to higher level questions only) begin on page 7 2012 no. 12 (b) [ordinary Level] State the laws of reflection of light. How would you estimate the focal length of a concave mirror? The diagram shows an object O in front of a concave mirror, whose focus is at F. Copy and complete the diagram to show the formation of the image of the object O.
Give one use for a concave mirror. 004 Question 12 (b) [Ordinary Level] A concave mirror can produce a real or a virtual image, depending on the position of the object. Give one difference between a real image and a virtual image. Use a ray diagram to show the formation of a real image by a concave mirror. A concave mirror has a focal length of 20 CM. An object is placed 30 CM in front of the mirror.
How far from the mirror will the image be formed? Give two uses for a concave mirror. Refraction 2005 Question 7 [Ordinary Level] Reflection and refraction can both occur to rays of light.
What is meant by the reflection of light? Describe an experiment to demonstrate one of the laws of reflection of light. The diagram shows a ray of light traveling from glass to air. At B the ray of light Explain what is meant by refraction. What special name is given to the angle of incidence I, when the effect shown in the diagram occurs? In the diagram the value of the angle I is 41. 80. Calculate a value for the refractive index of the glass. Draw a diagram to show what happens to the ray of light when the angle of incidence I is increased to 450.
Give one application of the effect shown in the diagram you have drawn. 2003 Question 7 [Ordinary Level] State the laws of refraction of light. Explain, with the aid of a labeled diagram, (I) total internal reflection, critical angle. The diagram shows a 450 prism made of glass. The critical angle for the glass is 420. Calculate the refractive index of the glass. The diagram shows a ray of light entering the prism from air. Copy the diagram and show the path of the ray through the prism and back into the air. Explain why the ray follows the path that you have shown.
Give two uses of total internal reflection. 2012 Question 12 (b) [Higher Level] The diagram shows a ray of light as it leaves a rectangular block of glass. As the ray f light leaves the block of glass, it makes an angle B with the inside surface of the glass block and an angle of 300 when it is in the air, as shown. If the refractive index of the glass is 1. 5, calculate the value of B. What would be the value of the angle B so that the ray of light emerges parallel to the side of the glass block? Calculate the speed of light as it passes through the glass. 011 Question 12 (b) [Higher Level] a ray diagram to show where the lamp appears to be, as seen by an observer standing at the edge of the pool. At night, when the lamp is switched on, a disc of light is seen at the surface of the winging pool. Explain why the area of water surrounding the disc of light appears dark. Calculate the area of the illuminated disc of water. (refractive index of water = 1. 33) Optical Fibers 2004 Question 11 [Ordinary Level] Read the following passage and answer the accompanying questions. Optical fibers are made of very transparent glass or plastic. The fibers contain at least two layers.
Guiding light in an optical fiber depends on how light travels through different media. Light waves are bent, or refracted, as they pass between materials of different refractive index. The amount of bending depends on the refractive index and the Engle at which light strikes the surface. Sometimes light cannot leave the material of higher refractive index. If it strikes the surface at a large enough angle, it is reflected back into the material. The critical angle, for what is called total internal reflection, depends on the difference in refractive indexes. An optical fiber guides light by using total internal reflection. Adapted from New Scientist, 13 October 1990) (a) Draw a diagram to show how a ray of light is transmitted through an optical fiber. (b) How is the escape of light from the sides of an optical fiber prevented? C) Name a material that is used in the manufacture of optical fibers. (d) What is the bending of light as it moves from one medium to another called? (e) What is meant by the refractive index of a material? (f) Define the critical angle. (g) When will total internal reflection occur? (h) Give one use for optical fibers. 2011 Question 7 [Ordinary Level] Light rays can undergo reflection and refraction.
Both of these can occur when light is traveling from a denser medium, such as glass, to a less dense medium, such as Give a practical application of the reflection of light. Explain, with the aid of a diagram, how total internal reflection can occur. What is meant by the ‘critical angle’ in total internal reflection? The photo shows an optical fiber which is used for the transmission of data using light waves. Draw a diagram to show how light waves travel along an optical fiber. Give two advantages of using optical fibers instead of copper wires when transmitting data.
Optical fibers are also used in medicine. Give an example of their use in medicine. 2004 Question 12 (b) [Higher Level] Give two reasons why the telecommunications industry uses optical fibers instead f copper conductors to transmit signals. Explain how a signal is transmitted along an optical fiber. An optical fiber has an outer less dense layer of glass. What is the role of this layer of glass? An optical fiber is manufactured using glass of refractive index of 1. 5. Calculate the speed of light traveling through the optical fiber. Speed of light in air = 3. X 108 m s-l 2009 Question 12 (c) [Higher Level] Information is transmitted over long distances using optical fibers in which a ray of light is guided along a fiber. Each fiber consists of a core of high quality glass with a refractive index of 1. 5 and is coated with glass of a lower refractive index. Explain, with the aid of a labeled diagram, how a ray of light is guided along a fiber. Why is each fiber coated with glass of lower refractive index? What is the speed of the light as it passes through the fiber? Light passing through optical fibers must travel through an enormous length of glass.
Impurities in the glass reduce the power transmitted by half every 2 km. The initial power being transmitted by the light is 10 W. What is the power being transmitted by the light after it has traveled 8 km through the fiber? (speed of light in air = 3. 0 x 108 m s-l) 008 Question 9 [Higher Level] What is meant by refraction of light? State Kennel’s law of refraction. An eye contains a lens system and a retina, which is 2. 0 CM from the lens system. The lens system consists of the cornea, which acts as a fixed lens of power 38 m-l, and a variable internal lens Just behind the cornea.
The maximum power of the eye is 64 m-l . Calculate how near an object can be placed in front of the eye and still be in focus; Calculate the maximum power of the internal lens. Light is refracted as it enters the cornea from air as shown in the diagram. Calculate the refractive index of the cornea. Draw a diagram to show the path of a ray of light as it passes from water of refractive index 1. 33 into the cornea. A swimmer cannot see properly when she opens her eyes underwater. When underwater: Why does the cornea not act as a lens? What is the maximum power of the eye? Why do objects appear blurred?
Explain how wearing goggles allows objects to be seen clearly. 2006 Question 7 [Higher Level] What is meant by the refraction of light? A converging lens is used as a magnifying glass. Draw a ray diagram to show how an erect image is formed by a magnifying glass. A diverging lens cannot be used as a magnifying glass. Explain why. The converging lens has a focal length of 8 CM. Determine the two positions that an object can be placed to produce an image that is four times the size of the object? The power of an eye when looking at a distant object should be 60 m-l. A person with defective vision has a minimum power of 64 m-l.
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Physics Optical Lenses. (2017, Oct 20). Retrieved from https://graduateway.com/physics-optical-lenses/