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SECONDARY EDUCATION CERTIFICATE

EXAMINATION

1 1 hours

1. You MUST use this answer booklet when responding to the questions. For each question, w

your answer in the space provided and return the answer booklet at the end of the examinati

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

steps in calculations.

Copyright 2002 Caribbean Examinations Council

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1. Table 1 shows the relationship between the temperature, T, of the measuring junction

thermocouple and the thermocouple emf, E, that is measured by a millivoltmeter.

Thermocouple emf Elm V 0 .1 0 . 4

0 .7 1 . 0 1 .4 1 . 8

Temperature TOle 4 4 1 1 8 1 6 3 2 0 2 2 4 7 2 9 3

Use the values in the table to plot E against T. Draw your BEST straighfline

(10 mar

Use your straight line graph to determine To ' the temperature at which

thermocouple emf E = O.

(ii) Use your straight line graph to determine, Ex' the thermocouple emf w

T = 2 0 0 C

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.: t- i ! t 1 t # - t i. .~... J. r..;-

...~:..,...!...j- .. :. ; ; ;. t i...t

+ .; . r :T :~ : ;T i : j : : :

!... . .-' + ~ f.. f t t

: : :

: ~ T ;: rTT:T

::t: :. ::. .

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(iv) Determine the difference between the experimental value as given in Table

that obtained using the formula in Part (iii), and explain the significance o

difference.

(v) Compare a thermocouple and a laboratory mercury in glass thermometer in

of (i) range (ii) speed of response (iii) sensitivity.

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Feature Common Dry Cell Car Battery

Size/weight LargeHeavy

Electrolyte Ammonium

Chloride paste

Emf

Electrodes Lead,

Lead Dioxide

Current Small to

Capacity moderate

(b) A generator and a battery of secondary cells are connected through an ammeter as

in the circuit ofFigure 1.

(ii) Show, on the diagram, the polarity of the ammeter for it to properly measu

current ( 1 m

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(c) A calculator battery of terminal voltage 3 V supplies a current of 0.1 mA to the calcu

circuit.

Write down the formula that defines the moment of a force, giving the meaning of Esymbol and the unit in which it is usually expressed.

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(c) Security guard posts in the Caribbean are usually equipped with a boom and counterweight

arrangement as shown in Figure 2. It allows the security guard to use a relatively small

force to raise the heavy boom.

A

( O.3m

,Path followed by \,

end of boom ...-... ~....

.

Counterweight

F A

Forceapplied

here

/////////////////

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(e) Use the results of (c) (i), (ii) and (d) above to find the mass of the counterweight that

be used if FA = 25 N is just enough to start raising the boom. ( 3 ma

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(b) Figures 3 and 4 below are representations of current-carrying conductors. Sket

magnetic field associated with the conductor ineach of the cases described below

(ii) The conductor is tightly wound into asolenoid carrying current inthe dire

indicated

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(c) A flat coil is connected to a small bulb and a diode. The assembly fixed in position near

a current-carrying solenoid is shown inFigure 5below.

(i) What will be the effect on the magnetic flux inside the flat coil if the current

through the solenoid is steadily increased?

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(iii) If the diode is removed so that the flat coil is connected to the bulb alone, indicate

by use of a tick ('./) which of the following effects will cause the bulb to glow

more brightly.

EFFECT YES NO

Increasing the number of

turns on the flat coil

Placing a piece of soft iron

in the core of the solenoid

Decreasing the rate of change

of the current through the

solenoid

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State the nature of the unbalanced force which is responsible for circular motion in

following:

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(b) A small bob of mass 0.2 kg is attached to a string oflength 0.5 m and whirled in a v

circle with a speed of 2.5 m/s as inFigure 6.

A

Bob in position A

B

Bob attached to string

(i) Indicate on the diagram the forces acting on the bob when it is in position

(2 m

(iv) If the.string is released when the bob is at C, what is the tension immed

after therelease of the string?

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