high school part 1 /2 by ssl technologies physics ex-48 click part-1 /2 study the terminology of...
TRANSCRIPT
High School
Part 1 /2
by SSL Technologies
Physics Ex-48
Click
PART-1 /2
Study the terminologyof parabolic mirrors.
Light rays
Physics Ex-48
Click
RULES FOR DRAWING RAYS IN CURVED MIRRORS
A ray that is parallel to the principal axis is reflected through the principal focus (F).
A ray passing through the principal focus (F) is reflected parallel to the principal axis.
A ray passing through the center of curvature (C) is reflected back along its own path.
Note that images have properties called "characteristics".
Image characteristics include:
LocationLocation of image (behind mirror or in front of mirror) Size Size (magnification) of image (larger or smaller than object) AttitudeAttitude (whether the image is inverted or upright) ReversedReversed (whether the image is reversed left-to-right, "mirror image")
Physics Ex-48
Click
CONCAVE MIRRORS
The characteristics of an image formed by a concave mirror dependon the location of the object. As it turns out, there are six “strategic”locations where an object may be placed. For each location, theimage will be formed at a different place and with differentcharacteristics. We will study the six different locations and labelthem as CASE-1 to CASE-6.
Case-1: Object at infinity
6
Case-2: Object just beyond CCase-3: Object at C (center of curvature)
Case-4: Object between C and F
Case-5: Object at F (focal point)
Case-6: Object between F and V (within focal length)
Be sure to studyeach case!
Physics Ex-47
Click
A ray parallel to the principal axis is reflected through the
focal point (F).
In order to draw images formed by curved mirrors, remember that :
FCPrincipal axis
Back of mirror
V
Physics Ex-47
Click
A ray that goes through the focal point (F) is reflected parallel to
the principal axis.
In order to draw images formed by curved mirrors, remember that :
FCPrincipal axis
Back of mirror
V
Physics Ex-47
Click
A ray that strikes the vertex (V) is reflected like a plane mirror. (Angle of
incidence = Angle of reflection)
In order to draw images formed by curved mirrors, remember that :
FCPrincipal axis
Back of mirror
V
Incident ray
Reflected ray
Incident ray
Reflected ray
Physics Ex-47
Click
A ray that goes through C(the center of curvature) is reflected back
along its own path.
In order to draw images formed by curved mirrors, remember that :
FCPrincipal axis
Back of mirror
V
Physics Ex-48
Click
This distance is known as the “focal length” (f).
fREMEMBER
The focal length (f) isfrom the focal point (F)to the vertex point (V).
Physics Ex-48
Click
Due to the great distance the object is from the mirror,all rays arrive at the mirror parallel to the principal axis.
As a result, all rays focus at the focal point and no imageis formed.
Object at infinity No image
Physics Ex-48
Click
Object just beyond C
Image is real,between C and F,
inverted and reduced.
Physics Ex-48
Click
Object at C
Image is real, located at C, inverted and
same height as object.
Physics Ex-48
Click
Object between C and F
Image is real, located beyond C, inverted and
larger than the object.
Physics Ex-48
Click
Object at F
All rays are reflectedparallel and thus
no image is formed.
Physics Ex-48
Click
Object between F and V(within the focal length)
Image is virtual, located inside the mirror,
upright and larger than the object.
Physics Ex-48
F
Object
Image
An object is placed in frontof a concave mirror.
Find the location and characteristics of the image.
TASK
C
C
There are two steps in finding the image of a concave mirror.NOTE
Draw a ray parallel to the principal axisand make it reflect through the focal point.
Step-1Draw a ray through the focal point and
make it reflect parallel to the principal axis.
Step-2
Object pointIncident ray
Reflec
ted
ray
Incident ray
Reflected ray
Where the two reflected rays meet is the image point of the object point.
Image point
Characteristics of the image
~ Real (formed by reflected rays)
~ Inverted (upside down)
~ Smaller than the object
Rather than draw an actual
object, it is easier to draw
the object as an arrow.
This way, we can tell if the
image is inverted or not.
Such asright here!
We can now draw the image.
Since we are not given the location of the object, we can select any arbitrary location.
Since the intersecting rays are both reflected rays,the image is real.
Back ofmirror
Objects consist of an infinite number of points.
And each point has an infinite number of rays radiating outwards.
Images also consist of an infinite number of points.
Each point on the object has a corresponding point on the image.
In locating an image, we take one point on the object and find its corresponding point (location) on the image object.
As shown above, we usually take the (extreme) top point
and find its corresponding point on the image object.ClickClickClickClickClickClickClickClickClickClickClickClickClick
Physics Ex-48
Click
For convex mirrors, the image is always virtual, always located inside the mirror,
always upright and always smaller than the object.
NOTE
Convex mirrors producea very large field of view.
Physics Ex-48Question-1
State the rules for finding the image formed by a curved mirror.
Click
1- A ray parallel to the principal axis is reflected through the focal point (F).
2- A ray through the focal point (F) is reflected parallel to the principal axis.
3- A ray through the center of curvature (C) is reflected back along its own path.
Click
Physics Ex-48Question-2
State four characteristics of images.
Click
1- Type (real or virtual)
2- Location (distance from mirror)
3- Magnification (size)
4- Attitude (upright or inverted
Click
Physics Ex-48Question-3
What is spherical aberration and how can it be eliminated?
Click
A fuzzy image produced by the fact that parallel rays do not passthrough the focal point (F).
It can be eliminated by making the mirror parabolic rather thanspherical.
Click
Physics Ex-48Question-4
The diagram below displays a concave mirror and a beam of lightstriking the mirror. Label each part.
ClickClick
Focal plane
Principal axis
Reflected ray
Concave mirror
Vertex (V)
Focal point (F)
Physics Ex-48Question-5
The diagram below illustrates the image of an object producedby a concave mirror. Label the incident ray, the reflected rayand the extended ray.
ClickClick
Extended ray
Incident ray
Reflected ray
Physics Ex-48Question-6
For each concave mirror below, draw the image.
ClickClick
a)
Image
Image is real(formed by reflected rays)
Physics Ex-48Question-6
ClickClick
b)
For each concave mirror below, draw the image.
Image
Image is real(formed by reflected rays)
Physics Ex-48Question-6
ClickClick
c)
For each concave mirror below, draw the image.
Image
Image is real(formed by reflected rays)
Physics Ex-48Question-6
ClickClick
d)
For each concave mirror below, draw the image.
Image
Image is virtual(formed by extended rays)
Physics Ex-48Question-7
The diagram below shows an illuminated object and its virtualimage in a concave parabolic mirror.
Determine the location of the focal point (F).
ClickClickClick
C
F
REMINDERThe focal point (F) is half
the radius of curvature (C).
Physics Ex-48Question-8
The diagram below shows an object in front of a convex parabolicmirror. Draw the image.
Click
Image is virtual,upright and smaller
than the object.
Image
Physics Ex-48Question-9
Where must an object be placed in front of a concave mirror so as to form an image that is:
a) Smaller than object? ____________________________________
b) Inverted? ____________________________________
c) Virtual? ____________________________________
d) Inverted and magnified ? ____________________________________
e) Same height as object? ____________________________________
Click
Just beyond the center of curvature (C).
Beyond the focal point (F).
Within the focal length (f).
Between C and F.
At the center of curvature (C).
Physics Ex-48Question-10
Consider a convex mirror, where must an object be placedso as produce a real image?
Click
Impossible, convex mirrors do not produce real images.
Physics Ex-48Question-11
State the properties of a virtual image.
Click
A virtual image is formed by extended rays.
Physics Ex-48Question-12
In what important way does a virtual image differ from a real image?
Click
In the fact that a virtual image cannot be projected onto a screen.
ClickClick
Physics Ex-48Question-13
Consider an object placed in front of a concave mirror. Which oneof the following statements correctly describes its image?
Click
A) It is in front of the mirror, inverted, real and smaller than the object.
B) It is behind the mirror, upright, virtual, and smaller than the object.
C) It is in front of the mirror, upright, real and smaller than the object.
D) It is behind the mirror, upright, virtual and larger than the object.
Image
Back
Physics Ex-48Question-18
An object is placed in front of a convex mirror as illustrated below.
Draw and label the light rays necessary to locate the image.
Incident ray
Reflected ray
Extended ray
Incident ray
Reflected ray
Extended ray
Image
Click
Image is virtual, upright and reduced.
SSLTechnologies.com/science