..and here are three questions from a
1959 O level physics paper:
8. Answer two of the parts (a), (6), (c). (a)
Draw a diagram to show the shape and direction of the magnetic lines of force round a straight wire carrying a current of electricity. Describe how you would show the lines of force by the iron filings method, and give an explanation of how the filings act. (6) A uniform strip of nichrome, of resistivity 0.00110 ohm-cm., has a length of 200 cm., a width of 6.00 mm. and a resistance of 3.12 ohms. Calculate the thickness of the strip. If the strip is bent into the form of a square and its ends are soldered together, what will be the resistance between any two comers which are not diagonally opposite comers? (c) Draw a labelled diagram to show the circuit and the apparatus you would use to deposit a layer of copper on a brass spoon. What precautions would you take to ensure a firm, even deposit? Calculate the time taken to deposit 1.56 gm. of nickel using a current of 2.34 amp. in a nickel-plating process. [1.19 gm. of nickel are deposited per ampere-hour.]
b. An electric immersion heater is marked 12V 72 W. Describe, with the aid of a circuit diagram, an electrical method of checking this marking, given an accumulator battery of e.m.f. 13V as the source of supply. Give one reason why the heater should be immersed in water during the experiment. Calculate the rise in temperature which the heater can cause per minute in 500 gm. of water when the heater is connected to (a) a 12 V. supply, (b) a 13 V. supply.
[1 joule is equivalent to 0.24 calorie.]
10. Draw a labelled diagram of an a.c. step-down transformer. Explain how the transformer acts. Give reasons for any special features in the shape and structure of the core of the transformer.
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Clearly we educate our children much better these days. /sarc off
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Topic: Can anyone guess where these questions appear? (Read 1211 times)