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FACULTY OF ARTS.

PRELIMINARY HONOUR PHYSICS.

Heat and Light.

1. Explain as fully as you can why the scale of the constant volume hydrogen thermometer has been selected as the standard physical scale of temperature. Use the following heads :

(a) Necessity for defining the scale from the behaviour of a definite substance under definite conditions.

(b) Reasons for the choice of the constant volume conditions.

(c) Reasons for the choice of Hydrogen as the standard thermometric material.

2. Establish the equation for the adiabatic curves of a gas obeying the relation PV=Rm1.

3. Show that for a gas obeying Boyle's Law, a fall in temperature produced by expansion through a "porous plug" indicates forces of attraction between the molecules of the gas.

4. (a) Give the physical interpretation of the relation

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(b) Transform this so as to express it in terms of quantity of heat energy and interpret it as thus transformed.

5. (a) Describe a method for the production of a zone plate and show that the system thus formed will act as a lens of definite focal length.

(b) Give the width of the central disc of a zone plate in terms of its focal length.

6.. (a) What are "visibility curves"?

(b) Illustrate from the case of the light from a sodium flame.

7. (a) State the "Law of Fermat".

(b) Show that the law of the extreme path leads to Snell's law Li.e. sin i i

sin r

μ.

8. Discuss under the following heads the present situation in regard to wave length tables.

(a) Rowland's method of coincidences.

(b) Reasons for a revision of Rowland's values. (c) The method of Fabry and Perot.

FACULTY OF ARTS.

PRELIMINARY EXPERIMENTAL HONOUR PHYSICS.

Laboratory Paper.

Candidates may omit either 6 or 7.

1. From the data given you below, write a complete report on the calibration of a simple nickel-iron thermo-couple. Length of potentiometer wire=100 cm. Resistance of potentiometer wire 10 ohms.

E.M.F. of standard cell=1.019 volt.

Temperature of cold juncture=0°C.

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2. Give two methods of measuring the wave-length of sodium light. Describe one of them in detail and state which you consider the more precise, giving reasons for your an

swer.

3. Describe, by the aid of diagrams, two standard methods of measuring the resistance of an electric conductor. Compare the two methods and state which you would use for measuring a very low resistance.

4. (a) Why is the graphical method of representation of experimental results preferable to that by tabulation?

(b) A straight line graph when properly drawn should make approximately an angle of 45° with each of the coordinate axes. Why is this so?

5. In order to determine the surface tension of a liquid from the height it rises in a capillary tube, you are provided with a travelling microscope operated by a screw with a graduated head of 100 divisions. If one turn of screw advances the microscope 1 mm., find the per cent. error in each of the following determinations of "T" due to an error of one division in the reading on the screw head. (Neglect other sources of error).

cm.

cm.

(a) diameter of tube=0.24 mm. ; height of liquid=11.9

(b) diameter of tube=1.20 mm. ; height of liquid=2.4

What does your result tell you with regard to the best experimental arrangement for an accurate determination?

6. Describe clearly the construction and use of a "biquartz" with special reference to the determination of the strength of a sugar solution by an optical method.

7. (a) Describe a method of comparing the moments of inertia of bodies of regular shape.

(b) Name at least four experiments in which you dealt with harmonic motion.

FACULTY OF ARTS.

PRELIMINARY HONOUR PHYSICS.
Electricity and Magnetism.

(Candidates will write on eight questions only).

1. (a) Define electrical potential at a point and show how it is related to electric intensity.

(b) Apply Gauss' theorem to prove that the electric intensity due to a uniformly electrified infinite plate is equal to one half that just outside a cylindrical surface having the same charge of electricity per unit area.

2. Give a rigid proof of the Inverse Square law, stating on what experimental fact your proof is based. How was this fact demonstrated?

3. (a) Write a note on Faraday's conception of electric action.

(b) Making use of his ideas, establish a mathematical expression for the electric intensity at a point.

4. Discuss the construction and theory of Lord Kelvin's quadrant electrometer and state the particular arrangement you would use to measure potentials of less than I volt.

6. (a) Discuss mathematically the behaviour of Faraday tnbes when they cross the surface of separation of one dielectric from another.

(b) Use your result to show that we may look upon a conductor as a dielectric of infinite specific inductive capacity.

6. (a) State the fundamental assumption in establishing (1) the mathematical theory of Faraday tubes, (2) the mathematical theory of magnetic tubes of induction.

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