頁二第張六第日十初月三年戌庚夏 WAH KIU YAT PO
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1770英文中學會考試題預習專欄
坚道英文書院主編
物理科
(四)
PHYSICS (24)
SOLUTIONS
Luminous intensity of the old lamp
200 candela
Distance from the table
*q = 10 ft.
Luminous intensity of the combination of two lampe
21, 400 candela
Illumination on the table
400
foot-candela
100
4 ft-ed.
Luminous intensity of new lamp
**2 * 160 candels
Distance of the new Tamp from the table ». Sinos equal
mination is obtained
200 100%
0.94
Ana. The Illumination at the centre of the table.
is 4 ft-çd. The new Lamp should be placed 8.94 ft. above the centre of the table.
The Lamp is 2 ft. below the mirror. Enero 15 ao image of the lanp 4 ft. above the lamp, Luminous intensity of lamp
Luminous intensity of its image
100 0.P.
80 0.9.
Distanos of its image above the road – 24 10. The illumination immediately below the lamp is due to bosk I and
Intensity of illumination
100
80
24
0.389 lumen/sq.ft.
Ane. The illumination of the road vertically
below the lamp is 0,389 lumen/öq.ft.
Propagation of Light
Though light is a kind of transvOZUS, VAVO (the plane of vibration of the medium is at right- angles to the direction of propagation of the energy) light travels in straight lines. This is known as the Rectilinear Propagation of Lights
Proofs This ia avident from the fact that we not see through three pin-holes on cann
hree separate cardboards, if the holes
not placed in a straight line.
consequence of the rectilinear propage= tion of lighti⠀⠀
Shadows a
1
abra and penumbra regiona
Eclipse of the heavenly bodies
total eclipse of the sun partial eclipse of the sun annular eclipse of the sun, sast also the lunar eclipeas.
Pan-hole effect Pin-hole camera
Reflection at a plane surface
When a wave of light strikes an object placed
in its parth any, or all of the following three.
`may happen..
1.
The incident light is partially absorbed and converted into heat Reflection occurs
If the object is transparent, or trans- lucent, a part of it passes at a reduces speed and if the incident path in oblique, it will be deviated.
When a light ray is incident upon a reflectin sur- face, it is reflected in such a manner that the anɛ. of reflection, measured with respect to the normal to the surface, is equal to the angle of incidence also measured with respect to the normal. Moreover, both angles and the normal lie in the same plane. This phenomenon is known as regular reflection Laws of reflection
(1) The incident ray, the reflected ray, and th normal, at the point of incidende are all in the same plane.
(2) The angle of incidence, equals the angle or reflection
郭日橋
三期星5日五十月四年〇七九一届公年九十五粛民華中 育教僎造
These lave are well accounted for by the wave theory which is beyond the syllabus of "orm 5, however they are verified in the laboratory with the aid of pins and papers.
Images of Plane Mirror
Images formed in a plane mirror. ars
1. virtual
2. upright (erect)
3.
laterally inverted with respect to the object same size as the objer
as far behind the mirror as the object in front
Rotation of a Plane Mirror
When a plane mirror ia rotated through an angl 3, each reflected ray is turned through an angle. aqual to 26
Inclined Mirrors
If two plane mirrors are inclined one to another, so as to make an angle of between them. and if a point object be placed between them, the number of images produced 1s
No. of images
Parallel Mirrora
360
When an object is placed between two parallel mirrors an observer sees a great number of images in
straight row behind each mirror,
Theoretically,
No. of images
360
infinity
Practically, the reflected rays weakened
after several reflections. Images become progrea sively fainter and fainter,
Spherical Mirrors
Theer are two types of spherical marróra
Converging mirrors....
Concave mirrors,
The polished surface 18 in the inner surface of the sphere.
Viverging mirrors
Convex MITTOTS
The polished surface is in the out side of the sphere.
Principal parts of a Spherical Mirror
Principallaxie: the line of symmetry
mirror AB Pole or centre of figure:
The mid-point P of the mirror incipal focus: The intersecting point on the principal axis by the reflect ion of parallel incident raye or their produced.
ture: With which the surface of the mirror is described;0-
Imagea formed by a Concave mirror
Images formed by a concave mirror CHI VE formed by any two of the following reflected rays
1. Incident raye parallel to the principal
axıb and are reflected through the focus Incident rays passing through the princi- pal focus are reflected parallel to the principal ax16,
3. Rays passing through the pole and are not
When the object is at infinite distance the 10 age is real, very small, and formed at the Principal focus.
(B) When the object is placed at a considerable
distanos from the concave mirror, beyond the centre of curvature, the image is real, dim- inished, lioe between the principal focus and the centre of curvature and is inverted.
(C) When the object is brought etell nearørtne m mirror the image becomes larger and approaches the centre of curvature.
(5)
then the object ie at C the image is also at C it is inverted and is the same size as the obs
ject. In this case the object and image are said to be self-conjugate.
the object in between C and F the image real, inverted, enlarged and is formed further 'from the mirror than ◊
Then an object is placed at the principal focus the reflected raya aze practically parallel, 10 images is formed.
is the object approaches to the mirror, that is Inside the focus, the reflected raya are "diverg- ant, and never intersect, unless they are pro- iuced backward, so that no real image is formed The produced rays intersect at the back of the mirror, the image is virtual, enlarged, erect.
Images on Convex Hirror
The convex mirrors produce only virtual images. of real objects. These virtual images are analler than the object, they are srect and are at the bagi- of the mirror,
Formula and a1e7-501vention, for spherical Mirrors
The general formula connecting the focal Length f, object distance ù, and the image distance. ✔, in spherical mirrors ie
(未完轉入第六張第三百》
文中學
學會考試題預習專欄]
英文科
(廿四)
王淑方
CAJ㵑箱少時,會不足,去學,又不成。項梁起之。籍曰:「雙足以約名姓而已。刻一人敵 *不足學,學蒍人做。」於是項榮乃執籍兵法,猶大書、感知其震,又不會死學。其藥霞有
59738 IN DIE WIE ZA AIR DEERE DES RAHIMA » ZUGE » EIGA ·MERAARE.
奥中餐士大夫家出现架下。梅买中有大無畏及賽,有架常為主靜,能以兵洗部勒賓客及于鹅
,以是知其能。秦始皇帝游會積,渡浙江,妮與籍供觀。經曰:「铁可取代。」架掩其
AB: [EXT › ERI JRNEAM •
(B)宋人有路其苗之不是而堪之權。茫然節,個共入曰:「今日丽买于助苗要矣!]关于淋
眉往确之*苗則偊矣。天下之不助苗長借蠢矣
,坯茁者也॰非徒無益,而又養之。
LESSON TWENTY-FOUR
1970
SECTION FIVE
TEST PAPERS
Answers to Test PAPER II No. V
(1) (C)
(9) (F)
(2) (B)
((6) (T)
(10, (Q)
98
TEST ONE (ENGLISH PAPER III
Answer ALL Sections:
SECTION A
Read the following passage carefully:
(A)
1301
38
When I got to the Kantak Airport, I realized tha the plane from London, on which my siter was travell- ing, had been delayed at Singapore with engine troub). and was expected to be about two hours läte, As a rule I can kill my time quite happily, watching the planes land and take off, but that evening I had a headache, which I thought that the noise of the engines. might make worse. I determined, therefore, to walk around to make the time pass quickly
First of all I went back to the car park, where had left my car to make sure that all the doors were locked. The walk in the fresh air did me good, for
I felt slightly better as I entered the main airport- building again. I made my way to the restaurant, where I ordered a cup of lemon tea. As I stood drinking thị at the counter, I studied the faces of the people. around me. Some passengers were obviously anxious about the time, and kept looking at their matches; others checked to see that they had tickets, passporta and money. Where there was a group of people, it was easy to tell which one was about to leave, lie was the object of everyone's attention and looked either very happy or very sad at the thought of departure. There. was one old woman who burst into tears as she said goodbye to the relatives, or friends who had come to see her off.
When I had finished my tea, I went along to the bookstall, where I bought a couple of magazines, both of them about travel, which would help to make the time pass pleasantly, Then I went into one of the wait- ing-rooms and made myself comfortable in a big armchair I had hardly had time to open one of my magazines when. someone came up and put his hand on my shoulder. It was an old friend, who was just about to leave on a business trip to Japan. Since we had not seen each other for a long time, we found plenty to talk about until the arrival of my sister's plane from Singapore was announced.
Now answer these questions from the information given in the passage:
For each of the following voras or phrases ind a word of similar meaning in the passage:
(a)
decided
Sericial documents snowing travellers identity
happily and agreeable
going away
Learnt
proclaimed, gave notes on
(2) Why did the writer go to the airport? (3) Why did the writer go back to the car park?
•·(4) How could you tell, according to the writer
which person in a group was about to leave: (5) When was his sister's plane about to arrive? (6) Did the writer usually like watching the plane
land and take off?
(7) Did the writer take any interest in the other
people in the restaurant?
(8) Where was the writer when his friend found him?
SECTION B
Translate the following passage into Chinese:
One summer evening I was sitting by the open window, reading a good but rather frightening mystery story. After a time it became too dark for me to read easily, so I put my book down and got up to switch on the light. I was just about to draw the curtains as well when I heard a loud cry of "Help! Help!" It seemed to come from the trees at the end of the garden. I looked out but it was now too dark to see anything clearly. Almost immediately I heard the cry again. It sounded like a child, although I could not imagine how anybody could need help in our garden, unless one of the boys of the neighborhood had elvshed a could not get down.
SECTION C
tree
Translate ONE of the following passages into Englishaj