Science C1+2 Flashcards
Angle of incidence
The angle of incidence is measured from the normal. An angle made by a light ray or wave hitting a surface and the line perpendicular to that surface. An example of an angle of incidence is the angle between a light hitting a table and a line perpendicular to the table. According to the law of reflection, the angle of incidence is equal to the angle of reflection.
Angle of reflection
The angle between the reflected ray and the normal is the angle of reflection. OR The angle that a ray of light or the like, reflected from a surface, makes with a normal to the surface at the point of reflection.
angle of refraction
Refraction is the bending of the path of a light wave as it passes across the boundary separating two media. In such a case, the refracted ray will be closer to the normal line than the incident ray is; this is the FST rule of refraction. Refraction is caused by the change in speed experienced by a wave when it changes medium.
binocular
They are simply two short refracting telescopes fixed together. Binoculars are not as powerful as telescopes but they are much more convenient. Binoculars have two reflecting prisms on each side. binoculars take advantage of lenses to manipulate light.
concave lens
A concave lens is thinner in the centre than at the edges. As parallel rays pass through a concave lens, they are refracted away from the centre of the lens. So as light passes through a concave lens, the light rays diverge or spread out, and they will never meet on the other side of the lens.
convex lens
A convex lens curves outward and is thicker in the middle than at the edges. The technical name for a convex lens that curves outward on both sides is a double convex lens, but it’s usually just called a convex lens. As parallel light rays travel through a convex lens, they are refracted toward the centre of the lens. So as light passes through a convex lens, the rays move toward each other. The light rays cross at the focal point of the lens. Convex lenses bend parallel light rays to a single point. As a result, the concentrated light energy at that point is hot enough to burn skin and can start fires. The ability to bring light rays together makes a convex lens useful for two reasons. First, it can act as a light collector, much like a concave mirror. This is why a convex lens is used in a refracting telescope. It collects and focusses starlight. Second, a convex lens forms a real image. The light rays actually meet at a point, and the image can be projected onto a screen.
converge
light converges through convex lenses, and light diverges through concave lenses. By putting these lenses in front of the eye, you can alter the angle at
which light enters the eye. For people whose lenses cannot converge light enough, convex lenses are prescribed.
concave mirror
A concave mirror has a surface that curves inward like a bowl. Like any other mirror, concave mirrors obey the law of reflection. However, when parallel light rays approach a curved surface and strike at different points on the curve, each ray will reflect at a slightly different direction. These rays all head to a common point, called the focal point. concave mirrors are good at collecting light and bringing it to a single point. This is why concave mirrors are ideal for reflecting telescopes where you want to gather as much dim light as possible.
convex mirror
A mirror with a surface curved outward is called a convex mirror. As you might expect, it does the opposite of a concave mirror. Instead of collecting light, it spreads out light rays. A convex mirror reflects parallel rays of light as if they came from a focal point behind the mirror.
Focal point
rays all head to a common point, called the focal point. the point at which rays or waves meet after reflection or refraction, or the point from which diverging rays or waves appear to proceed. (for concave) If an object is farther from the focal point, the image is upside down. If the object is between the focal point and the mirror, the image appears upright and enlarged.
Incident rays
An incident ray is a ray of light that strikes a surface. The angle between this ray and the perpendicular or normal to the surface is the angle of incidence.
intensity
Ray diagrams can help explain why the brightness, or intensity, of a light changes with distance. Figure 2.3 shows the same number of rays leaving the light source, but fewer hit your eyes as you move farther away.
Luminous
A light source is luminous; it produces light. Light
from a light source (the sun, a lamp) bounces or reflects off the pencil and hits your eyes.
microscope
All microscopes allow you to see great detail by combining the power of at least two lenses. These two lenses are the eyepiece and the objective. When a light
source shines through the specimen, a large image is produced that you can see by looking through the eyepiece. microscopes take advantage of lenses to
manipulate light.
Non- luminous
Pencils and other opaque objects are non-luminous, meaning they don’t produce light. The light that gets to your eyes from the pencil is actually light reflected from a
light source.
normal line
a line perpendicular to the mirror at the point of reflection is called the normal. angles are measured from the normal.
opaque
Opaque materials do not allow any light to pass through them. They absorb or reflect the light that hits them. Since light cannot get through an opaque object, a shadow is created behind it. Wood, metal, and brick are examples of opaque objects.
