-15 MAY 1968
莫三弟强六第
日九十月四年申戉壓夏
WAH KIU YAT PO
0968
CITY HALL
日五十月五年八六九一联公年七十五國民事中
英文中學會考試題預習專欄
The first reflection is at the convex mirror.
object distanze ul
- 20 cm.
300.
AC2
物理 科
(廿九) ·陸永爟·
Focal length of the convex mirror_• 5))}
10 cm.
300
(t. candle
Image distanceiv
302
The illumination at C due to`lamp 8.
-
Physics (29)
300
20
000 0.
5. Solution
CBX
20
Γ 300
[AC]
CB2
CB
(a) i) Characteristics of Images formed by s ̄plans] ·
4
mirror*:-
(1) Image position. The image is as far
behind the mirror as the object is in front.
(2 It is erect relative to the object."andi
le the same size,
(3. Lateral inversion.
(4
It is virtual. No light energy rea ches) the region behind the mirror, so the image cannot be formed on a screen,
The principal focus of a conarve mirror is the point on the principal axis through which all rays originally parallel to the. azia sasa after reflection.
(b) Determins tion of the focal Innotb of a concaveĮ
mirror.
ans. The first image is, wherefore, a virtua
one,16 cm,behind_the_mirror?,
İyne`second"reflection is at the conca veļ mirror. The virtual image of the convex mirror constitutes the object.j
object distance,• 42**
[Focal length ̋á
(4+ 62)-ema
462 cm 1
The concave mirror 20 cm) Image_distance...”.
300 x 30
√302440232
9000
50
ft candle
Total illumination at C due to both lambe
2
300 302
9000
503
*0.333 +0.073 (-10.405 ft. candle
/8)
Focus eye on) object pin
2
3
20
12
[Ans. The second image is geal and is formed
"at a distance of 1219. cm in front of
the concave mirror.
7. Tal fuman eve and Vémera
D
11) Illumination"at"D"due_to_each_lamp]
300
08
object "aving\
The concave mirror is susported vortiMLIJ in a mirror-holder. An optical pin, stucked i a cork, is adjusted so that the tip of the pin / Lies on the principal axis of the mirror, The pin is then moved along the bench in front of the ndrror until a real inverted image of the pin is then moved to and fro until there is no paralia, between the oin and its image. The distance between the mirror front and the optical sin is measured which is the radius
of turvature of the mirror, Its focal length is) half of this value.
Human Eye
A light-tight box
back A film at the
"An aperture varies the ime of exposure and thus the amount of
energy incident
A geommodation is made by means of moving the lena. towards or away from the film,
Permanant image is developed by chemicals on the "negative",
Camera
A light-tight Retina lined setisory cellar
Lerotic
The size of the pupil adjusted the "rådial" and "ring" muscles of the iris regulates the incident light.
Accommodation is
possible as: the curva turej of lens varies
automatically on seeing, near and distant objects,
The brain interpreta Sensation into a temporary image.
300 &D,
OR
300 x 30
1333
9000
46870
- 192
+ 20733
Illumination due to both lamps,
- 0.197 x ?
1. 0.384rt-candles;
the given ortam. mpressanta cha Dash of
the say thr
the prsand F. Being the point of tatal
Legion
2
horam is a G and 'inconsmet al d..
The animum angle of emergenas LNÍ MÍ given by the minimum angle of total reflection at f. It la, unmreforg, täm
Fince JPCG to concyelis, in
FG 1200"
+420- 180
et ton at
· 60
glese tole
HONG
11) Short-sight
This is due to:-
(a) eyeball" too long, or
(b) over-fatigue of ciliary muscles so that the lens in its resting state have a focal length less than the distance to the retina. Image of distant objects are formed nearer to the lans than the retina, A short sighted eye usually has its - nearest point of distinct vision at distance of less than 10 inches.
It de corrected by using spectacles with concave lenses. These make raya from objects more divergent before entering the sye, so that image formed by the eye lana i further back than when the spectacles are absent..
8. Sölution given "next"week")
Questions—for next week-
RE
Đen aribe the action of a simple ̈ce LL, Zhenics)
explain the terms:
polarization
(1)
(11)
111)
local action
E.M.F. of a cou
(b) (1) State Ohm's Law,
(11) Describe, and explain briefly, with the help of labelled diagrams, how to use a voltmeter and an ammeter to meBSUPE (1) a very high resistance
(2) a very low resistance
(e) Each cell in the circuit has an 8,n,t,” of
KONG PERIC LIBRAY
2 volts and an internal resistance of 1 ohm, (1) Find the currant through the lamp.
(11) The heat produced in thế 20 ohms resistor in'
one hour.
A
(111) The mass of copper dañosited on the ›
cathode of the copser voltameter in 30 min.) The internal resistance of the voltameter La 5 ohms,
ه طریقه تم
(electrochemical equivalent of copper.
- 0.00033 cm /coul, ),
Errefors
1.5 sintàco.
telescope
Lana
An electrio: wätte.
-FIT:
3 ce Lia)
'20 n
ID 2
rked
...! fööni "length of object lens,
*.g. starTRY
are sensibly
(1) What does this meaḥ? 1) Calcul to the resistance
(114) Calculatesthe cost of eléctri
$0,3: net Thit; af 2 of these
in series, are swibo
.connected, to a
of
Copper Volta-
The ter