You are provided with two retort stands, two metre rules, pieces
of thread and other nec es s ary apparatus.
(i). Set— up the apparatus as illustrated above ensuring that the
strings are permanently 10 cm fiom either end of the rule.
(ii). Measure and record the length L = 80 cm of the two strings.
(iii). Hold both ends of the rule and dis place the rule slightly, then
release so that it oscillates about a vertical aXis through its
centre.
(iv). Determine and record the time t for 10 complete os cillations.
(v). Determine the period T of os cillations.
(vi). Evaluate log T and log L. Solutionwap.net
(vii). Repeat the procedure for four other values of L = 70, 60, 50
and 40 cm.
(viii). Tabulate your readings.
(ix). Plot a graph with log T on the vertical aXis and log L on the
horizontal aXis.
(X). Determine the slope, s, and the intercept, c on the vertical aXis.
(X). State two precautions taken to ensure accurate results.
[21 marks]
*(b).*
(1). Define simple harmonic motion [2 marks]
(ii). Determine the value of L corresponding to T = 128 fipm the
graph in (a) above.
[2 marks]
*2(a).*
You are provided with a beaker, a thermometer, a stirrer, stop
watch/clock, measuring cylinder, table salt, water and other
nec es s ary materials .
(i). Measure 200 cm3 of water into the beaker.
4
(ii). Heat the water until it boils steadily for about 2 minutes.
(iii). Read and record the boiling point b0.
(iv). Add table salt of mass M = 10.0 g to the boiling water and
stir continuously until another boiling point b1 is attained
(v). Read and record b1
(vi). Evaluate 6 = (br- ho).
(vii). Using the same mixture, repeat the procedure four more
times by adding 10.0 g of salt each time to give the cumulative
mass Mjofsalt as 20 g,30 g,40gand50 g.
(viii). In each case allow the mixture to boil steadily for at least 2
minutes then read and record the boiling point bi.
(ix). Tabulate your readings.
(x). Plot a graph with M- on the vertical axis and 0 on the
horizontalaxis.
(xi). Determine the slope, s, of the graph.
(xii). State two precautions taken to ensure accurate results.
[21 marks]
*(b).*
(i). Define the boiling point of a liquid. [2 marks]
(ii). What effect does impurities have on the boiling point of a
liquid? [2 marks]
*3a)*
You are provided with cells, a potentiometer, an ammeter, a
voltmeter, a bulb, a key, a jockey and other nec es s ary materials.
(i). Measure and record the emf E of the battery.
(ii). Set— up a circuit as shown in the diagram above.
(iii). Close the key K and use jockey to make a firm contact at]
on the potentiometerwire such such that P] = x = 10 cm
(iv). Take and record the voltmeter reading and the
corresponding ammeter reading .
(v). Evaluate log V and log I
(vi). Repeat the procedure for other values of x = 20, 30, 40, 50
and 60cm.
(vii). Tabulate your readings.
(viii). Plot a graph with log I on the vertical axis and log V on the
horizontal axis.
(ix). Determine the slope, s, of the graph.
(x). Determine the intercept, c, on the vertical axis.
(xi). State two precautions taken to ensure accurate results.
[2 1marks ]
*(b).*
(i). Howis the brightness of the bulb affected as x increases?
Give a reas on for your answer. [2 marks]
(ii). List two electrical devices whose actions do not obey Ohm’s
law. [2 marks]
*ANSWERS
TO THE QUESTIONS ABOVE*
*1.*
This experiment involves Bifilar suspensions the motion of
which should be like when opening a tap.
In part (a) candidates are expected to:
– Measure and record five values of L to at least 1 d.p. and in
trend. Trend: As L increases, t decreases
– Evaluate five values each of T, log L and log Ito at least 3 s.f.
– Record data in composite table. Solutionwap.net
– Plot five point, correctly using reasonable scales and
distinguished axes.
– Draw line of best fit.
– Determine the intercept on the vertical axes and the slope of the
graph us ing large right- angled triangle.
– State any two of the following precautions in acceptable
language.
– Ens ured supports of pendula were rigged.
– Avoided parallax error on meter rule/ stop watch.
– Zero errorwas noted and corrected on metre rule/ stop
watch/ clock
– Ens ured smooth and regular os cillations in a horizontal plane.
– Repeated readings shown on table.
Part (b) expected answers are:
Simple harmonic motion is the motion of a body whos e
acceleration is always directed towards a fixed point and is
proportional to the displacement fiom the fixed point.
T = 1.2 secs
Log 1.2 = 0.079
0.079 shown on graph with corresponding log L read
L correctly determined.
*2.*
The aim of this experiment is to investigate the effect of
dis 3 olved s alt (impurity) on boiling point of water.
The expected answers are:
Value of hi read and recorded in °C.
Five values of hi read and recorded in °C to 1d.p and in trend.
(Trend: As M increas es, bi increas es)
Five values of M correctly recorded in gram.
Five values of 6 = (bi – b0) correctly evaluated to 1d.p.
Composite table showing bo,bi,1V[j, and 6.
Candidates are also expected to:
— Plot five points on graph.
– – Distinguish between the axes.
– – Choos e reas onable s cales.
— Draw line of best fit.
— Determine the slope of the graph.
— State any two of the following precaution in acceptable
language.
– – Avoided splas hing of water.
– – Avoided parallax error on thermometer/ stopwatch/ clock
– – Avoided noted zero error on stop watch/ clock
– – Ens ured thermometer did not touch the beaker.
– – Repeated readings shown on the table.
— No drop of wateris allowed to escape after weighing.
– – Thermometer not allowed to rest on the has e of beaker.
– – Stirred after adding 3 alt to ensure dis 3 olution.
(b).
(i). This is the temperature of a liquid at which the saturated
vapour pres sure of the liquid equals the extemal atmospheric
pres s ure.
Impurities increase the boiling point of a liquid.
NB: The graph should looklike the one below.
*3.*
In part (a) candidates were required among other things, to:
– Measure and record the emf of the battery involts to at least 1
d.p.
– Read and record sixvalues of, V and Ito at least 1 d.p and in
trend. (Trend as increases, V and I also increases)
-Evaluate sixvalues of log Iand log Vto at least 3 d.p.
– Record V, I, log V and log I in composite table.
– Plot six points correctly using reas onable s cale.
– Drawline of best fit on distinguished axes.
– Determine the slope of the graph using large right angled
triangle and recording of the intercept on the vertical axis.
State any two precautions in acceptable language
– Ens ured clean/ tight terminals.
– Open key when reading was not taken.
– Avoided parallax error in ammeter/ voltmeter.
– Avoided sliding of jockey on the potentiometer wire.
b(i).
– Brightnes s of the bulb increas es.
-Voltage/ current through the bulb increas es.
(ii). Devices that do not obey Ohm’s law.
Diode
Trans is tor
Thyris tor
Capacitor
Therrnis tor
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