1961-06-15 — Page 2

1 18 unknown; and it, is by reference to these conditions that joy and appreciate his skill. Even the most unsophisticated. noe realizes in some measure that the playwright is an artist ating a picture of life under such-and-such, assumptions and Fations, and appraises his skill by its own vague and instinctive dards. As our culture increases, we, more and more consistently

this attitude, and take pleasure in a playwright's marshalling of ial in proportion to the skill he shows. In many cases, indeed pleasure consists of a delicate blending of surprise with anti-

on. We foresaw, and are pleased to recognize, the art of the Pachievement, while details which had grown dim to us give us

its little thrill of fresh admiration. Regarded in this aspect, at play is like a great piece of music: we can hear it again ano

with ever-new realization of its subtle beauties, its comple: phies, and with unfailing interest in the merits and demerits of

particular rendering.

it we must look deeper than this if we would fully understand the

nature of dramatic interest. The last paragraph has brought us to erge of the inmost secret, but we have yet to take the final step. ve yet to realize that, in tnuly great drama, the foreknowledge ssed by the audience is not a disadvantage with certain incidental ations and compensations, but is the source ofthe highest pleasure,

the theatre is capable of giving us. We are, in fact, in the Lon of superior intelligences contemplating, with miraculous, voyance, the stumblings and fumblings of poor blind mortals ing through the labyrinth of life. Our seat in the theatre 10: a throne on the Epicurean Olympus, whenoe we can view with et intelligence, but without participation or responsibility, the cate reactions of human destiny. And this sense of superiority hot pall upon us. When Othello comes on the scene, radiant and dent in Desdemona's love, our knowledge of the fate awaiting him.

him a hundred times more interesting than could any mere ity as to what was about to happen. It is our prevision of Nora's at the end of the last act that lends its dramatic poignancy to

trance at the beginning of the first..

longevity : long life

retrospection: studying ourselves clairvoyance ability to see things not

present

ne following passage and answer the questions below:

brings us to a consideration of the part waion economic leader

be called upon to play in the coming social order. This ip is, broadly speaking of three kinds, which may or may not, ed in the same person. These are, first, directive and organising. hip; secondly, technical and administrative leadership

for

15

Post-Secondary Grant Colleges Joint Diploma Examination. 1961

Physics Paper

Heat and Thermodynamios, and Optics

Time: 3 nourg,

Answer SEVEN Questions with FOUR from Section A and THREE Trom section B

June 12, Monday

9.30 a.m. to 12.30 p.m.

1. (a)

(6)

2) (a)

(b)

5.

(a)

kæ }

6.

8.

9:

Seotion A

What is meant by black body radiation and now can it be realized) experimentally? Discuss the relation between the total radiation from a black body and its absolute temperature. Compare the rates of loss of heat from a body at 1000°C. and the same body at 500°C. if both are placed in an enclosure at 15°c.

I

A vertical wall .10 square meters is kept at a constant temperature: of 300°C. A layer of insulating material of thermal conductivity 0.0005 cal/sec. cm. deg. and of thickness 5 cm. covers the wall. The surrounding air is at atmospheric pressure and 20°C. Calculate. the heat lost per minute by conduction and natural convection. Give all the assumptions under which the calculation is carried out.

Explain what is meant by an ideal heat engine. vesorios clearly a Carnot, cycle followed by such an engine and state the conditions : for maximum efficiency.

An engine works in a Carnot cycle between the temperature of 100°C and 0°C. Calculate the work done in ergs if the heat taken in at the higher temperature is 10,000 calories.

A body of finite mass is originally at temperature T,, which is higher than that of a reservoir at T,. Suppose an engine operates in a cycle between the body and the reservoir until it lowers the temperature of the body from T to T2 thas extracting heat & from the body. If the engine does work W, then it will reject heat «-W to the reservoir. Applying the entropy principle, prove that the maximum, work obtainable is

W(max)

=

રે

T2(S1 - S2)

;

where S and S. are the initial and final values of entropy involved.

Explain entropy and discuss its relation to energy change ard. equilibrium.

Sketch the temperature-entropy diagram for water and saturated steam and show how it indicates that the specific heat of saturated steam is negative. What is the meaning of negative specific heat?

Define the five thermodynamic functions and explain' brierly the special usefulness of each of these functions.

3how. how the Maxwell's thermodynamic relations (equations) can be derived from these functions.

State the three laws of thermodynamics in their different forms and give one mathematical formulation of each law. Explain the physical meaning of each of these forms of the three laws.

Section B

Given two thick lenses. The first has radii of curvature of +4 and -. and an index of refraction 1.5. The second has radii of +3 and infinity and an index of refraction of 1.7. The thickness of each lens is 1 cm." and they are 1 cm. apart. Use the graphical method to locate the final, image point on the axis. Check your results by computation.

A convex lens of 1 metre focal length is laid on an 'optically flat" plane glass plate. Describe and explain what is observed when the system is viewed in monochromatic light reflected at about normal incidence. What measurements would you make to find the wavelength or the light used? How would you calculate the results?

Describe and explain spherical aberration, astigmacasm, coms, chromatic aberration, and distortion as found in lenses and mirrors. Give a method of correction for each of them.

(a) What is meant by Fresnel diffraction?.

Use this method to find the effect of diffration by a circular aperture,

(b) What is the difference between interference and diffraction?

What part does each play in the production of spectra by a diffraction grating?” How are gratings made and what is the effect of the number of lines on the spectra produced? What is the angular separation of the lines 5890 A and 5896 A in the second order spectrum produced by a grating having 5000 lines per on,?

-------00000-

administration is a branch of technique; and thirdly, human leadership. The best man of all to stand at the head of a great economic enterprise is one who combines all these three. Failing that, the best to dispense, with, in the man right at the top, is technical ability; for he who has the other two will know how to use technical ability where he finds it. The greatest difficulty arises when high organising capacity is divorced from the power of leading men, and has to manifest itself in driving them instead. This is a real dilemma; for organising and directive capacity are scarce, and society cannot afford simply to dispense with them when they are combined with other qualities inconsistent with democratic leadership. All it can do is to try to place them in positions in which they will have as little as possible to do witn ordering other people about, or to temper their autocracy by setting beside them, on governing boards or commissions, men who excel ini human leadership, even if they have less.pre-eminence in organising power,

The technician, unless he possesses organising“ability or humanı leadership in addition to his technical or professional skill, is unsuited for executive control. His function is none the less important, but it is advisory. The case against technocracy rests on the. Frequency of the divorce between technical ability and the other

English -7Rhetorio