頁二第張四第日四廿月八年寅丙曆夏
1987
中學會考試題預習專欄
物理(一)
Revision. Ex
Cert. Exam (1987)
PHYSICS (1)
MILL & DALE PRESS LTD.
This course provides the candidates of KCER 1985 a general revision in Physics. Brief notes, and revision 'exerçise" for each section are for revision purpose. Solutions for exercises after each section will be given in the following
SECTION A
OPTICS
Chapter One Reflection
1.1Reflection at plane
surfaces
Law of Reflection
1.The incident ray, the reflected roy and the normal at the point of incidence are on the same plane..
2. The angle of
incidence is equal to the angle of reflection, (t.e
WAH KIU YAT PO
0 is the object, AC and BD are two of the
reflected rays received
by the observer. The reflected rays appear. to diverge from I, which in the image of the object. The insge is virtual,
Note:Areal image is
one through han which the actual light rays poss (ive, it can be put on, and
screen. An virtual image is one from which light rays appear to diverge (3.e. it cannot be put on a screen).
Properties of image. fürned by ́plane. mirror
() virtuul. (ii) erect
(iii) Taterally.
inverted
(iv) same size as the
object
(7) es für behind the mirror as the object is in front.
1.2Reflection at curved
mirrora.
Spherical curved
irrora
報日僑華
Aapherical mirror is. one whose reflecting surface is part of the [surface of a spheres.
The centre of corvature
is the centre of the sphere. The radius of the sphere is the radius of curvature of the mirror. The principal focus of a spherical mirror is the point on the principal axis to which all rays parallel and close to the principal axis converge (or from which they appear to diverge) after reflection from the mirror. If the focal length of a spherical mirror (concava or convex) is f and the radius of carvation is 8, then
Ray diagrams are dravn according to the rules. listed below:
1. Rays passing through
the centre of curvature: pre reflected back along their own patha⠀⠀ Rays parallel to the principal axis are reflected no se to: pass through the focus for concave mirror and appear diverge from the focus for convex mirror,
Raya through the focus of a concave mirror, or rave- towards the focus
a convex mirror are reflecter parallel to the principal axis.
Example
Find graphically, the nature of the image. formed by an object
5 cm tall, placed 40 in front of a CONCAVE mirror of focal length. 15 cm.
following ray diagrams C, Fand P are the centre of curvature,
focus and the pole of the concave mirror. respectively, m
Let usobject distance
v-image distacce and f-focal length
Ray diagrama
(i) w> 2£
(fi) uref
(iv) u=f
Plane MirrUE-
When an object is placed in front of a plane mirror, all the reflected ray, when produced backwards, vill meet a paint
bebind the pirror,
This point is called
the innge of tho
object. As shown the roy diegran below....
Spherical.
Concave mirro
Ans:
The image is real, inverted and diminished. It's size ja Jen.
(a) Concave sirrer
The po ture of an
image formed by a
concave pittor Vort with-
difference in position
of the object. In the
(b) Convex mirror
六期星
日七十月九年六八九一年五十七國民華中 育教聞港
because they are.
magnified
magnified!
real
real
real
virtual real:
· inverted
erect
The properties of the images formed by concave and convex mirrors;
one paint
inverted
diminished
inverted same size:
.
FRIČA"
:00 A
U= **
> 21.
fu< 21
=1
P
Concave
mirror
經濟 (
Revision
07-A
virtual, erect, diminished and behind the mirror
Convex.
mirror
Exercise
Cert. Exam. (1987)
ECONOMICS (1)
MILL & DALE PRESS LTD.
Banfe Concepts
Wants
People have many wants, ranging from
the primary wants arising from the biological require- ments such as the ne need for food and drink, to the second- ary wante crented and determined by culture such as the desiras to watch movie, listen to music, study at university, etc.
Since resources available for each individual are. limited, he or she cannot bove all hie or her wants
t
satisfied, but only
Bone of them,
Therefore, for each individual there is n hierarchy of wants.
Wants which are basic
and important will be given the first priority and will be satisfied first.
2. Utility
By utility is meant the level of satisfaction which s
person obtains when .consuming a certain.
commodity. The measurement of utility.
is subjective and. varies from person to person, as well as
from commodity to commodity. Different people may obtain different utility when consuming the sane commodity.
As a person
increases the consumption of a certain commodity: by
one unit, the extra level of satisfaction he obtains is called Marginal Utility. Marginal Utility tends
to diminish as one increases the amount of the consumption of
a certain commodity successively, This is called The Law of M Diminishing Marginal Utility. Wealth
Wealth, can be defined as stock of goods existing at particular time, Wealth possesses utility and money value. It is limited in supply and capable. of being transferred. Wealth can he of an individual, a society, an organisation, a nation, or the world. Economic and free
Goods are defined as those which yield satisfaction to the consumers who use them. They can be classified as free goods and economic goods."
Free goods nre unlimited in. supply. e.g.pairy sunshine. They do not bear prices becauséa consumers can get them for use as many as they need,
Economic goods are
limited in supply. They bear prices
demanded by consumers.
but cannot be supplied with unlimited · quantities, e.g. car pen, house, book, etc.
Scarcity and Choice
People's wants are many, but resources for making goods and services are limited in supply Resources are scores in the senge that everyone VanLe cannot be
satisfied fully or forever, even wher all resources have been Woll utilised to produce ganda and services. Therefore, it is natural that people's Innumerabile wants are constrained by, limited supply of natural resources in the world. 'Scarcity:" arises when everyone. tries to maximise hia total level of " satisfacti ou derived from the consumption. of certain comidities and services.
As scarcity arises, people' must make a choice since they. cannot have all their. vants satisfied fully: They have to sacrifice some of their wants in order to meet other needs. Choice is. therefore very important for every índividual as long as scarcity of resources exists.
Opportunity cost
- Since scarcity of resources exista ang people must make choice in arranging resources in different lines of production; the production of certain commodities implies the sacrifice of other commodities' that could be produced by the same resources,
By the opportunity - coat of pruduction is meant the alternatíve used of factors of M production which are......... necessarily sacrificed- by using those resources, in a particular way.
For example, a person with a certain amount of money can buy a new car or a new hont. If he buys: the car, the opportunity cost of his action would be
the boat.
十月初舉行首次會董會議,互選正副會長及推定各部部長。
展朱
市祖
彩色華僑
華僑日報
逢星期日利出
周海媚時時提醒自己要謹
物業市道暢?
天的家具
息
康快
偶像
提供
香港布廠商會年會
「和廣州設立了辦事處。以外資銀行來說,匯整委国會當然委員。侯德回任後,螅文停任 官a桀克越停止哲理
新署委會
· 香港旅遊協會執行總幹事江航空諮詢。
沈弼接受訪問看好經濟前景
後專司時,准
〔特政府憲報昨日公佈港各已批
程向交署理財政司
何鴻鑾署任布政司
政務官。問經昌任商品交易事務監察委員
香港人遊香港
東平洲。塔門 秋日歡樂暢遊
(1)乘遊覽車遊西貢區風景秀麗如畫 (2)漫步北潭涌郊野公園獵影留永記
(3)專車直達黃石碼頭備專輪往塔門
(4) 新漢記海鮮酒家嘗豐富海鮮午宴 (5) 漫遊塔門天后古廟弓背海灣攬勝 (6)專船往東平洲觀賞屉叠頁岩奇景 (7) 遊更樓石難過水龍落水氣勢不凡 (8)享日落歸帆美景載喩歸途樂無窮
(9) 晚餐於尖東興隆樓品嘗潮州榮式
情詢
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續
華僑日報
九月廿八日(星期日)
随報附送「彩色華僑」,並刊登多個特 大千世界:
立法局議員廖烈科談過去一年工作 核能正以極快速度發展
「軟木」用途廣泛,主要製造瓶塞 頭髮是確定人類種族最佳標記 眼淚可治痛傷·
美女最多的巴西 港產塑膠相架美而廉
鐵皮紙皮製文具圖案美
時事縱橫:
教育統籌委員會發表第二號報告書,提出、
百多項建議,其中改革預科課程,統一學、
前教育服務,開辦公開教育,俱有突破性
的經濟不是孤立的,因爲香港
K** # * # ** HI
酒的
大國的狀黨,例如美國、歐洲類同市場,中國今年下半年至明年; 購旗捐助,功德無量。 主要练權主義陰影。儘管如此, 援助無依,仁愛可風,
意,但唯一的威脅就是美國和歐洲方面的保護一蛟滿意的 己的經裤發展情形而定,今年香港的出口相當滿「港的經濟發展可望是比一
九月十七日保良局食斯避獄,
匯豐保持首席金融地位
·敬绣各界人士一致支持
,本期訪問了多位教育界及專業人士,陳敬九,
述高見,及探討分析各項建議的可行性。 假日精品:
社交舞虛頹俓雅怡人舞姿猶勝的士高 健身熱潮正盛學院開設林立 有名無實的皇家酒店旅客甘受惠待 香港首個飬鷂塲蜚聲海内外 科學家研究利用廢物代替蛋白質
讀料豐富,每份壹元