Refraction

Reflection When light reflects from smooth surface you can see an image. The image: - is _______ the object. (smaller than, the same size as, bigger than) - is _____ the mirror as the object is in front of it. (nearer than, the same distance behind, farther away than) - is virtual. It is not real. You cannot see it on a screen. -is laterally inverted. That means it is back to front. Light reflects from paper but you cannot see an image because the paper is _______. (smooth, rough) Copy and choose the right answers Draw the reflections.

Reflection When light reflects from smooth surface you can see an image. The image: - is the same size as the object. - is the same distance behind the mirror as the object is in front of it. - is virtual. It is not real. You cannot see it on a screen. -is laterally inverted. That means it is back to front. Light reflects from paper but you cannot see an image because the paper is rough.

How can we see transparent objects?

Reflection & Refraction

Refraction

Experiment to show that the light ray bends towards the normal when it goes into a more optically dense material. Method: -Set up the light box so that a ray of light enters the glass block. -Draw round the glass block and draw two crosses on the incident ray and the emergent ray. -Draw a dot where the incident ray goes into the glass block and where the emergent ray comes out. -Move the block and light box and draw in the position of the rays as in the diagram below. -Measure the angles and write them in the table. -Repeat for another angle of incidence. Angle of incidenceAngle of refraction Table of results

Results Complete this text with these words: away, less, more, shallower, straight, towards The experiment shows that when light goes from a _______ dense to a ______dense medium, the light bends _______ the normal. When light goes from a more dense to a less dense medium, the light bends _______ from the normal. The reason for this is that light travels more slowly in an optically _______ dense medium. So the side that hits the more dense medium first slows down first. This is why when you look into water from above the water looks _______ than it really is. Your brain thinks that light goes in ___________ lines and that the bottom of the swimming pool is higher than it really is.

Results The experiment shows that when light goes from a less dense to a more dense medium, the light bends towards the normal. When light goes from a more dense to a less dense medium, the light bends away from the normal. This is why when you look into water from above the water looks shallower than it really is. Your brain thinks that light goes in straight lines and that the bottom of the pool is really higher than it is. Optics/zX0a6a7b01014b4e727a7f7b.htm

Air Water The Kingfisher Refraction of light is the bending of light rays when they go from one substance to another Refraction

Air – less optically dense Water – more optically dense The Kingfisher When light passes from a more optically dense substance into a less optically dense substance the light rays bend away from the normal to the surface. normal Refraction

Air – less optically dense Water – higher refractive index The Fish When light passes from a less (optically) dense substance into a more optically dense substance the light rays bend toward the normal to the surface. normal Refraction

Air – less dense Glass – more dense Glass Window Air – less optically dense Refraction Light passing through a transparent material exits at the same angle it enters

Uses

Refraction Refraction of light is the bending of light rays at the interface of dissimilar substances When light is passing from a higher refractive substance into a lower refractive substance the light rays bend away from the perpendicular to the surface. When light is passing from a lower refractive substance into a higher refractive substance the light rays bend towards the perpendicular to the surface. The angle at which the light is bent depends on the Refractive Indices of the two substances