images formed by a concave mirror vii std science (state syllabus)
TRANSCRIPT
Images Formed by a Concave
Mirror
VII std Science
(State Syllabus)
B. Dhandapani
Teacher Educator
Block Resource Centre Sarva Shiksha Abhiyan
Mannargudi BlockThiruvarur District
Tamil Nadu
Email [email protected]
Project Done by:
To understand the basic principles of Ray optics
To understand the principles of “Construction” of ray diagrams
To explain how the images are formed by the concave mirrors for various positions of objects
Basic Principles
Terms Used in Concave Mirrors
Construction - Title
Construction 1
Construction 2
Construction 3
Images Formed - Title
Object at Infinity
Object beyond ‘C’
Object at ‘C’
Object between ‘F’ and ‘C’
Object at ‘F’
Object between ‘P’ and ‘F’
All in One
Relative Movement of the Object and the Image
Ready Reckonor
Uses of Concave Mirrors
Test Your Understanding
Click on the headings to study the relevant topic
Spherical Mirrors are Portions of spherical surfaces
If the outside of the spherical mirror is silvered, then it is called a concave mirror
Concave Mirror
Index
Pole (P) (C) Centre of Curvature
The Line Passing through C,P – Principal Axis
Terms Used in Spherical Mirrors
P – Pole
C – Centre of Curvature
Principal Axis
Geometrical Centre
Centre of the sphere of which the mirror is a part
Index
Index
Principal Axis
Construction 1
F
Ray Parallel to Principal Axis
Rule 1. The Ray Parallel to Principal Axis is reflected through the Principal Focus ‘F’
Index
F Principal Axis
Construction 2
Ray Passing through ‘F’
Rule 2. Ray Passing through the principal focus ‘F’ is reflected parallel to the Principal Axis .
Index
F Principal AxisC
Construction 3
Rule 3. The ray passing through the Centre of Curvature ‘C’ is reflected through the same path.
Index
Index
F C
All the Rays of the Object at infinity are parallel to Principal Axis and hence according to Construction 1 the image is formed at ‘F’.
Index
F C
There are two rays emerging from the object which is placed beyond ‘C’. One ray is parallel to Principal Axis and the other ray passes through ‘C’. Both the rays meet at the point between ‘F’ and ‘C’ where the image is formed.
1
2
Index
F C
There are two rays emerging from the object which is placed at ‘C’. One ray is parallel to Principal Axis and the other ray passes through ‘F’. Both the rays meet at the point ‘C’ where the image is formed
1
2
Index
F C
There are two rays emerging from the object which is placed between ‘F’ and ‘C’. One ray is parallel to Principal Axis and the other ray passes through ‘C’. Both the rays meet at the point beyond ‘C’ where the image is formed.
21
Index
F C
There are two rays emerging from the object which is placed at ‘F’. One ray is parallel to Principal Axis and the other ray passes through ‘C’. Both the rays meet at the point of infinity.
2
1
Index
F C
There are two rays emerging from the object which is placed between ‘P’ and ‘F’. One ray is parallel to Principal Axis and the other ray passes through ‘C’. Both the rays meet at the back of the mirror when the rays are extended. The virtual image is formed at the back of the mirror.
P
1
2
Index
P
CF
Object @ Infinity – Image @ ‘F’ – Real, Inverted
Object beyond ‘C’ – Image between ‘F’ & ‘C’- Real, Inverted
Object @ ‘C’ – Image @ ‘C’ – Real, Inverted.
Object between ‘F’ & ‘C’ – Image beyond ‘C’ – Real, Inverted
Object
Image
Infinity
…All in One (Recap)
Index
Object
Image
When the Object moves closer to the Mirror,
The Image Moves away from the Mirror
Index
SlNo Place of the Object
Place of the Image Formed
Rays to be Drawn Nature of the Image
1 At Infinity At ‘F’All Rays Parallel to Principal Axis (PA)
Real, Inverted, Small
2 Beyond ‘C’ Between ‘F’ & ‘C’
Ray 1 Parallel to PA & Ray 2 Through ‘C’
Real, Inverted, Small
3 At ‘C’ At ‘C’Ray 1 Parallel to PA & Ray 2 Through ‘F’
Real, Inverted, Same as Object
4 Between ‘F’ & ‘C’
Beyond ‘C’Ray 1 Parallel to PA & Ray 2 Through ‘C’ Real,
Inverted, Large
5 At ‘F’ At InfinityRay 1 Parallel to PA & Ray 2 Through ‘C’ --
6 Between ‘F’ & ‘C’
At the Back of the Mirror
Ray 1 Parallel to PA & Ray 2 Through ‘C’
Virtual, Large, Straight
Index
•Used in search light, car lights and telegraphic intermittent lights.
Used in mirror telescopes (its front is a silver-plated mirror)
•The spherical concave mirror finds its most valuable application as eye mirror (Helmholtz 1851). It serves during examination of the inside of eyes.
Click on pictures to get notes
Index
Click on Boxes near the answers and know whether Your Answer is Correct or needs correction
Click- For Correct Answer You will hear
Click -For the incorrect answer You will hear
Click on Boxes near the answers and know whether Your Answer is Correct or needs correction
Click- For Correct Answer You will hear
Click -For the incorrect answer You will hear
Index
1 Spherical Mirrors are Portions of
2. Concave Mirrors have the silvered surfaces on the
Spherical Surfaces Plain Surfaces
Rough Surfaces None
Outer Side Inner Side
Both the Sides Top Side
Index
3. The geometrical centre of the concave mirror is
Radius Pole
FocusPlane
4. Centre of the sphere of which the mirror is a part is called
Centre of Curvature
Pole Radius of Curvature
Principal Focus
Index
5. The line passing through ‘Centre of Curvature’ and ‘Pole’ is known as
Radius of Curvature
Principal Axis None
Principal Focus
6. The Ray Parallel to Principal Axis ‘P’ is reflected through
Principal Focus ‘F’
None
The 2f
Between ‘F’ and ‘2f’
Index
Through ‘F’ itself
Parallel to Principal Axis
Through ‘C’
Through Principal Axis itself
Through ‘F’
8. The line passing through ‘C’ is reflected 24
On the Principal Axis Parallel to Principal Axis
Through ‘C’ itself
7. The line passing through ‘Principal Focus’ is reflected
Index
Formed Beyond ‘C’
Formed at ‘C’ Formed at infinity
Formed at ‘F’
9. When the object is between ‘F’ and ‘C’, the image is
10. The image is formed at infinity when the object is
At ‘P’
Between ‘F’ and ‘C’
At ‘C’
At ‘F’Index