LIGHT Measuring Angles

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Ilene Thompson
5 years ago
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1 1. Using a protractor LIGHT Measuring Angles This angle is 33 Put vertex (corner) of angle where lines cross One arm of angle goes through middle of 0 This angle is 45 Measure these angles: 66 Light an introduction page 1

3 LIGHT Introduction 1. Light travels in straight lines. 2. Light travels at km/sec = 3 x 10 8 metres / sec = km / h. 3. A ray is a thin line of light. a ray 4. A beam is a thick bundle of rays of light. a beam 5. A mirror reflects light: incident ray reflected ray mirror 6. A lens, or glass, transmits light. {ie light goes through it.} Lenses often refract {bend} the light ray. Light is refracted when it goes from one substance to another. {eg from air to glass, or from water to air.} incident rays refracted rays 7. Glass is transparent {light is transmitted; you can see through it clearly. rosted glass or some plastics are translucent {light comes through but you cannot see clearly through it}. Wood, metals etc. are opaque. Light is not transmitted; you cannot see through them. 8. White is not a colour. White is what you see when all the colours of the visible spectrum are mixed together. Black is not a colour. Black is what you see when no light enters your eyes. Black is when there is no colour at all. We say the colour of glass, water and air is clear, or colourless {and transparent}. 9. We can use a triangular prism to break white light into the different colours of the visible spectrum {like a rainbow}. These colours are: red orange yellow green blue indigo violet Light an introduction page 3

4 1. transformer / rectifier {also called a power source} ray box {or light box} 2. Mirrors LIGHT Equipment New Words transform = change mirror = plane = flat convex = curving out concave = curving in bi = 2 biconvex = both sides curving out biconcave = both sides curving in concavo-convex = one side curving out and one side curving in plane mirror concave mirror convex mirror 3. Lenses biconvex lens biconcave lens concavo-convex lens 4. Prisms rectangular prism triangular prism semi-circular prism

5 Light Reflecting in a Plane Mirror 1 - slit plate plane mirror transformer ray box ray box incident ray normal reflected ray plane mirror i = angle of incidence r = angle of reflection i r Experiment Results: i r 1 2 Experiment onclusion: Light an introduction page 5

6 Experiment #1 Experiment #2

7 A ircular oncave Mirror = centre of curvature (the centre of the circle that the mirror is part of) R = radius of curvature (the radius of the circle) = principal focus of the mirror f.l. = focal length of the mirror principal axis f.l. R mirror (part of a circle) principal = main, most important axis = a line Images in oncave Mirrors These rules are true for circular and parabolic (part of a parabola) concave mirrors: an incident ray parallel to the pricipal axis is reflected through the principal focus. an incident ray going through the principal focus is reflected parallel to the principal axis. if reflected rays from the same point on an object really meet at a point, then the image is real. if the reflected rays only meet behind the mirror, the image is virtual. ind the images and describe them: A image nature: location: size: Light an introduction page 7

8 B image nature: location: size: image nature: location: size: D image nature: location: size: Light an introduction

9 Light Revision Exercise 1. Write the number of the meaning (on the right) in the box next to the correct word. One has been done for you. 10 ray beam reflection refraction opaque object lens translucent object transparent object transmit absorb 1. light passes through, but you can t see clearly through it 2. happens in a mirror 3. light does not pass through it 4. take inside and keep, like water in a sponge 5. when light rays are transmitted, but bent 6. a thin line of light 7. allow light to travel through 8. a thick bundle of rays of light 9. light travels straight through it 10. a transparent object that refracts light 2. Write four different objects in each column: non-luminous objects natural luminous objects artificial luminous objects 3. Write the number of the reflected ray in the box: Light an introduction page 9

10 4. Draw and describe the image in the concave mirror: image nature: location: size: 5. Draw and describe the image in the convex lens image nature: location: size:

11 Light an introduction page 11

When light strikes an object there are different ways it can be affected. Light can be

When light strikes an object there are different ways it can be affected. Light can be transmitted, reflected, refracted, and absorbed, It depends on the type of matter that it strikes. For example light