TEST CODE 002494/2FORM TP 97112/2

SECONDARY EDUCATION CERTIFICATEEXAl\1INATION

Ii hours

In addition to the I} hours, candidates areallowed a reading time of IS minutes. Writingmay begin during the IS-minute period.

1. You MUST use this answer booklet when responding to the questions. For each question, writeyour answer in the space indicated and return the answer booklet at the end of the examination.

2. ALL WORKING MUST BE SHOWN in this booklet, since marks will be awarded for correctsteps in calculations.

Copyright 1996 duibbean Examinations Council. iAll rights reserved.

Place the sheet of board provided under the opposite page and then put the semi-circularglass (or perspex) block flat down on the page. If necessary, use thum btacks to keep theboard in position.

Locate the CENTRE of the diameter of the block and insert a pin at this point. Usingthis pin and one of the others as an incident ray, plot the passage of a ray oflight throughthe block. (See Figure I below.)

Repeat the procedure for a different angle of incidence and find a second value of therefractive index.

(b) Figure 2 below shows a circuit used to control the current through a fixed resistor. Thevariable resistor is made from a length of resistance wire.

A student made the following statement after testing this circuit: "When the length of theresistance wire in the circuit increases the current increases. Therefore the current, [,through the fixed resistor is proportional to the length, x, of resistance wire, so that[ = constant x x."

Set up the circuit in the diagram below and, by measuring the current for THREE differentlengths, test whether this statement is correct.

Resistancewire

Fixedresistor

(a) Set up the apparatus as shown in Figure 3 above. Attach the spring balance to the loop of threadat the 50 cm mark and hold the spring balance so that the rule is horizontal. Record thedistance,y, in cm, of the object from the pivot, as well as the reading on the spring balance, F.

Vary the position of the unknown weight on both sides of the spring balance, and repeat theprocedure to obtain six pairs of values of y and F. ;I)

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,Find the slope, G, of the graph.

45 emGiven that G = ---W-' find W.