育教傋 真三第張四第 日九十月四年香已滕 WAH KIU YAT PEONY
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CITY HALL
明星
日三月六年九六九一曆公年八十五國民華中
He as on:
(接第四張第二页):
英中會考物理科答案
(牆) *陸永熾·
when
Relation between object distance. distance and the focal length
i mà ce
(1) the inverse-square Law of Illumination
The
Lumination of a surface by a point.
source is inversely proportional to the distance from the source.
E is the intensity of illumination
is the luminous intensity dis the distance from the source.
Luminous intensity, b 40
c.p Distance from the source, d; -2. £t. therefore
the
tensity of allumination le
An impu Lae, of compression at the mouth presses the air molecules down: the. tube. Simultaneously, a reflection of an impulse of rarefaction goes up to the the mouth..
whe resu
the object distence vis the mage distance
f the focal length of theirs
All distances are measure and
centre.. Distances of read real cages are positive.
tne optica
Distances ol
virtual objects and images are negative. The focal lengths of converging lenses are real and, be positive."
The focal lengths of diverging leases far
cual and by neatly
10 tt-cand te
Replacing the white screen by a black screen, much of the light energy 19 absorbed and diffused. Illumination Is much reduced.
iv) A perfect reflecting mirror will reinforce
the intensity of al lumina taun. on
Despite a one vertical or horizontat position of the tuning fork, sound waves. are emitted spherically. Resonance does occur in any of the two positions Livey,
(V) Actually the antinode of the fundamentat
of the stationary wave is somewhere up the mouth of the tube, The distance of this antinode from the moù this determined. by the diameter of the tube and is called the..'ead-corretion
2/4 - (l+ c)
linear magnificatio
the height of the images
The the Tgi
the abject and is usually denoted by
image size
object size
the
lowing di
found that
ABAC USI BĽ
IB VA
IC
ELTE)-A TRỳ diagram of an assrun'amical
Vitrinity
virtual
image al
distant object
illumination due to the 40-ev.
source
illumination due to the mirr
10/9.
total ilumination
fe-candle
The
The light source is on the centre of curvature of the concave mirror. image of this source due to the conca mirror is also on the centre of curvature
Ine Lota.i viiùmination
nerezore
0.9 x 40
ft candle
via the velocity of sound fis the frequency
2 is the wavelength
e la. the end-correction.
When a vártage of a.c. supply 18 ACTOAS the sonometer wire, 8 suitable value of wire length AB and tension T is adjusted, A maximum amplitude of vibration indicates a full resonance is obtained. Another position of A and B is readjusted and also the tension of the wire, and the appropriately that of the manets, ko obtain another reïonundelofy the wire. This id done for several values of AB and Finally, the mass of per unit lenztli of the wire is found.
(a) The direction of ground wave in the cube
during resonance
Compress? DA
Bærafaction
OBJECT LENS
common
focal l
EYE LEN
reflectea
Ef given, en h reflected
As the prang ́ex a vibrating FALKEMİZ Tork moves downwards through half s vibration, it sends a pulse of compression down the tube which is reflected on reaching the water eurface, back to the month of the tube.
At the moment she" compression renTDM'S. the top, the prong has just reached the lovest posi ta on, and starte moving upwards It will now send a rarefaction down the tube This, rarefaction will also be reflected to the top at same time". as the
completes a vibration.
ther
At this stage the prong has made oar complete vibration and has sent aut bäs
of sound.. The sound
completed up and down the
wave has twice Lube.
That is, the length of the atr column is one-quarter of a waveletsih.
ASTRONOMICAL
TELESCO
It is difficult to repre- sent the longitudinal tranave THO wave disgraus matically, it is custom- ary to represent it by transverse waxe en rva nashwona
overlapping pools
of light projected
on a white screen
from 3 projectors
(by)
overlapping.
sheete
of coloured glass seen against a white blackground
BLUE
GREEN
A
BLUE
GILLEN
C
RED
RED
D
WHITE
BLACK
(iv) Velocity of sound.
and
where is, the absolute temperature.
there
Le T
In notter rooms, the resonance leng gumag of the air column should be longer in order to have a resonance. It is pro- portional to the square-root of the abɛom. lute temperature of the room.
A-C. Sup
graph of IT agarast £ is plotted. ratio of FT/l is obtained,
Mai
frequency'
frequency of the resonant wire
-2121.5
980 XY OY
where M 18 mass per unit langth
of the wire
is the acceleration
due to gravity.
Tis the tensionor vire
is the length of wire
(c)
Velocity of sound Velocity of wind
750 m.p.h.
Time taken for sound to reach B
750... 50
3600
800
Time Laken to reflect back to a
750 3600 .700
50
Bec.
"Potare time taken
3600/100 x (~ + =)
36 x 15
56
9.65 sec
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再四第四第日九十月四年司機 WAH KIU YAT PO