Astrophysics
,22nd
February 2024 Telescopes :
Refracting Telescope
Parallel
Convex Lense
Riagrams for Rays
3
& ·
I &
-Light Rays that are parallel when
entering lens
,
------
7 -
object is
infinite distance
away , Im
ciple axis
focal point (*)
-
-Convex lenses cause to
converge the
at
3
rays
(
1 f
-Distance between centre
of lens a
focal point is
optical
axig focal length (4) ·
my when
object of infinity
.
Parallel
-If Rays aren't parallel to principle axis
,
focal point on
feplane
-........
Focal Plane
:Incident Rays
to earnote
a
pare
Note
-
Rays 't come
from infinity
-Ray not
from Infinity : Less man com
- 3
·
When
Rays come
from a point which equals the focal length,
they parallel to
leave eachother
.
- PA
Viewing from a dens
-s
Eye views
parallel rays as
if they've come
" from infinity.
------ -More
⑳
-
relaxing for eye
--
3
--
Y
S
S
-
I
-
Object therefor has been
magnified
S S
virtual S
S
, Drawing Ray diagram for Refracting Telescope ① Draw
② Gabel
eyepiece
fo
r
objective
life on
less
principle
I
!
co
axis-close to
eye piece
& *
.
Light from ③ make focus now fore .
infinity " ④
ray from focus
Draw a
S
through centre of
objective
·
lene.
I
⑤ Draw
rays from focus
S
2
top a bottom of
Y
S ro
!
Eye
pieon objective
⑥
Objective drawing left of
continue
Lens objective parallel ,
to
cenne
⑦ Draw ray.
conservation line
from focus through of eyepiece centre .
⑧ Pour 3
rays parallel from
bottom
of eyepiece moving right
.
,
⑨ Join 3
focus
to
⑳ Add
rays
labels
r arrows .
Magnification of Refracting Telescope
(m =
fo focal length of objective =
fe =
focal length of eyepiece
M =
no unit
Monday
Zom
February 2024 Subtended
Angles
Objects for away angles
-
are , subtended
small
(height of no
are
small approximations
object / angle
- use
E(
Length of hypotenuse length of
-s =
(d)
Distance
of object (d) adjacent
- sinf tan8 O
-Angle in radians :
(A =
1 I
-
angles
=
subtended
d =
distance
no =
diamete
Angular magnification
/M-00-angle
O
angle subtended
by image at
eye
=
,
subtended object at
by e
o
,22nd
February 2024 Telescopes :
Refracting Telescope
Parallel
Convex Lense
Riagrams for Rays
3
& ·
I &
-Light Rays that are parallel when
entering lens
,
------
7 -
object is
infinite distance
away , Im
ciple axis
focal point (*)
-
-Convex lenses cause to
converge the
at
3
rays
(
1 f
-Distance between centre
of lens a
focal point is
optical
axig focal length (4) ·
my when
object of infinity
.
Parallel
-If Rays aren't parallel to principle axis
,
focal point on
feplane
-........
Focal Plane
:Incident Rays
to earnote
a
pare
Note
-
Rays 't come
from infinity
-Ray not
from Infinity : Less man com
- 3
·
When
Rays come
from a point which equals the focal length,
they parallel to
leave eachother
.
- PA
Viewing from a dens
-s
Eye views
parallel rays as
if they've come
" from infinity.
------ -More
⑳
-
relaxing for eye
--
3
--
Y
S
S
-
I
-
Object therefor has been
magnified
S S
virtual S
S
, Drawing Ray diagram for Refracting Telescope ① Draw
② Gabel
eyepiece
fo
r
objective
life on
less
principle
I
!
co
axis-close to
eye piece
& *
.
Light from ③ make focus now fore .
infinity " ④
ray from focus
Draw a
S
through centre of
objective
·
lene.
I
⑤ Draw
rays from focus
S
2
top a bottom of
Y
S ro
!
Eye
pieon objective
⑥
Objective drawing left of
continue
Lens objective parallel ,
to
cenne
⑦ Draw ray.
conservation line
from focus through of eyepiece centre .
⑧ Pour 3
rays parallel from
bottom
of eyepiece moving right
.
,
⑨ Join 3
focus
to
⑳ Add
rays
labels
r arrows .
Magnification of Refracting Telescope
(m =
fo focal length of objective =
fe =
focal length of eyepiece
M =
no unit
Monday
Zom
February 2024 Subtended
Angles
Objects for away angles
-
are , subtended
small
(height of no
are
small approximations
object / angle
- use
E(
Length of hypotenuse length of
-s =
(d)
Distance
of object (d) adjacent
- sinf tan8 O
-Angle in radians :
(A =
1 I
-
angles
=
subtended
d =
distance
no =
diamete
Angular magnification
/M-00-angle
O
angle subtended
by image at
eye
=
,
subtended object at
by e
o
