ch. 18 Flashcards
when you look at an object in the mirror, the image is
behind the mirror
When an object like a tree is illuminated by the sun, and you are looking toward the tree, light rays leave the object
from every point on the surface of the tree, and in every direction
Part complete
A ray of light impinges on a transparent material at some angle with the normal. If the material has a higher index of refraction, as it enters, the ray will ______________.
bend to make a smaller angle with the normal
What conditions are necessary for total internal reflection to occur?
angle 1 must be greater than the critical angle and n2<n1
what does angle of refracted light depend on
it depends on the indexes of refraction of the materials and the angle of the incident ray
When light hits the boundary between two different materials, it can undergo
both reflection and refraction
When viewing an object that is immersed in water, the image that is formed is __________.
a virtual image
The focal length of a converging lens is __________.
the distance at which parallel light rays are focused.
What does a negative magnification indicate?
inverted and real
The shape of a diverging lens is ______________.
thinner in the center than around the edges
The shape of a converging lens is ______________.
thicker in the center
if a lense creates a real image? is it converging or diverging
diverging lenses only make virtual images, converging can make ether
what is an extended source
it is a source where every point acts as a point source
what is a point source
it is a source of idealized light that emis rays in all directions
when will a point source or extended source be seen
they will be seen always, they have rays that emit from all directions and can be seen from all angles
when a ray is at an interface, what can happen
it can be reflected or refracted
when a light is in a material, what can happen
it can be scattered or absorbed
what is scattering
single rays are broken into weaker rays that point in all directions
when an object intercepts a point source, what happens
a sharp shadow is created
when a object blocks a extended source, what happens
there is a large collection of point sources that each produce their own shadow so the shadow is blurry and overlapped
what is the law of reflection
it states that the angle to the normal that the incident light makes, is the same angle that the angle of reflection makes with the normal
what are diffuse surfaces
they are surfaces that are rough and create reflected rays that point in many directions and do not produce an image
in a plane mirror, where do the rays come from? where do they appear to come from?
they come from object P, but appear to come from P’
what is a virtual image generally
it is the point where the reflected rays APPEAR to diverge from, but no actual light comes from this point
in a plane mirror, the image distance s’ is _____ to the object distance s
equal to
what is a virtual image
it is an upright image that appears to be the source of ray divergence
what is refraction
it is when light continues into a second medium but it bends or changes direction
when the incident light passes into a material with a larger index of refraction, what happens to the refracted ray
the angle gets closer to the normal
when incident light passes into a material with a smaller index of refraction, what happens to the refracted ray
it moves away from the normal
when does total internal reflection occur
when n2<n1, as the incident light angle increases, the refraction angle increases to 90° where it then reaches a critical angle and all light is reflected
when is there no total internal reflection
when n2> n1
A diverging mirror produces what kind of images?
only virtual images
what is a converging lens
it is a rounded lens that causes rays to refract toward the optical axis
for a converging lens, all rays that point initially parallel to the optical axis converge at the _______
focal point
what is the distance of the focal point from the lens called
the focal length
what is the near focal point
it is the point on which the light is incident
what is the far focal point
opposite side of near
for a converging lens, initially parallel rays will
refract through the focal point on the far side
for a converging lens, a ray initially passing through the focal point will
emerge parallel
for a converging lens, a ray initially passing through the center in a straight line will
continue in a straight line
A converging lens with an object outside the focal length (s>f) will create what type of image
an inverted real image
what are real images
points where the rays appear to converge
when the magnification is negative
the image is inverted, real
when the magnification is positive
the image is upright, virtual
what does it mean if s’ is negative
it means the image is on the same side as the object
for a converging lens, if an image is on the same side as the object what type of image is it, what is true of s’?
it is virtual, s’ is negative
what is the shape of a diverging lens
it is thinner at its center
where is the focal length for converging lenses
it is the distance from the lens to the point where parallel rays converge to
where is the focal length for a diverging lense
it is the distance from the lens to the point where the parallel rays appear to diverge from
for a diverging lens, what happens to parallel rays
they defract outwards and appear to diverge from the near focal point
for a diverging lens, rays that are directed toward the far focal point will
emerge parallel
for a diverging lens, rays directed at the center of the lens will
emerge through in a straight line
what types of images do diverging lenses make
they only make virtual images
what is a converging mirror
the parallel rays reflect and appear to converge to a point
what is a diverging mirror
parallel rays appear to diverge from the focal point behind the mirror
