Light Waves

• light is the form of energy that allows you to see the things around you
• describe the sequence of events to an object that enables you to see an object that does not produce its own light: light travels away from its source in a straight line. When it hits an object, it reflects (bounces off) and travel in a new direction. if the reflected light enter your eyes, you can see the object
• sources of light is called luminous oject
• example of natural luminous object is : meteor, sun and star
• example of artificial luminous object: candle, flashlight and lamp
• illuminated object is object that cannot reflect its own light and only reflect the light given out by the light sources
• illuminated object is an object that dont give out its own light
• incandescent light is a light that is emitted with heat such as the sun and candle
• luminescent light is the light that is emitted with out heat such as fireflies and angler fish
• light travel in a straight line
• when you shine a flash light or torch at night, you can see that light travels in a straight path
• when you are in a car at night, you can observe that the headlights shine on the things in front of the car but cannot light up the things around the corner
• light travels at 300,000 km/s or 300,000,000 m/s in a vacuum. a vacuum is an empty space so there is nothing that stops the light from travelling
• when a light ray reaches a surface, three things can happen: it can be reflected, transmitted or absorbed
• when an object absorbs light, the energy of the light is transformed into heat in the object
• when an object is reflected, the ray 'bounces off' the object. some materials reflect nearly all the light that hits them, others reflect only a little of it and absorb the rest
• when an object is transmitted, the ray passes through the object carries the energy with it
• the properties of material : transparent, opaque and translucent object
• transparent object allow the light to pass through them. Example: air, glass, pure water and some plastics
• opaque objects do not allow light to pass through them. Example: Cardboard piece and book
• translucent object allow light to pass through them partially. Example: tupperware bottles
• when an object dont reflect much light, it would be not clear and look like a blurry screen
• mirror reflects all the light that hits it
• if the light is reflected the ray leaves the object and keeps on travelling
• metallic surface are the best reflectors of visible light although darkly colored objects can reflect some light
• the law of physics that governs the way light reflects from object is called law of reflection
• law of reflection: 1. incident ray, reflected ray and normal line lie on the same plane surface 2. the angle of a incidence is equal to the angle of reflection
• normal line is always perpendicular to the surface / plane mirror
• the angle of incident is the angle between the incident ray and the normal line
• the angle of the reflection is the angle between the normal and the reflected ray.