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WAEC Physics Practical Answer – May/June 2017 Expo

100% Correct WAEC Physics Practical Answer Solution – May/June 2017 Expo Runs

Physics Practical Solution

2)

2b)
bi)The boiling point of a liquid is the temperature
at which the vapor pressure of the
liquid equals the pressure surrounding the liquid
and the
liquid changes into a vapor.
bii) impurities increases the temperature range a
substance can exist as a liquid


========================

(1)
TABULATE:
i:1,2,3,4,5,
L(cm):80.00,70.00,60.00,50.00,40.00
t1(s):17.87,16.22,16.09,14.08,13.28
t2(2):17.56,16.46,15.09,14.77,13.36
t(s)mean:17.715,16.340,15.590,14.425,13.320
T(t/10)s:1.7715,1.6340,1.5590,1.4425,1.3320
LogT(s):0.2483,0.2133,0.1928,0.1591,0.1212
Log L(cm):1.9031,1.8451,1.7782,1.6990,1.6021
Log T*10^-2(s):24.83,21.33,19.28,15.91,12.12
Log L*10^-1(cm):19.031,18.451,17.782,16.990,16.021
SLOPE(s)=(LogT2*10^-2 – LogT1*10^-2)(/Log L2 *10^-1 – LogL1*10^-1)
=(21.33-12.12(s))*10^-2/(18.50-16.02(cm)*10^-1)
=3.714*10^-1
=0.3714cm^-1

1axi)
i)ensured supports of pendula were rigged
ii)avoided parallax error on meter rule/stop watch

1bi)
simple harmonic motion is the motion of a body whose acceleration is always direct towards a fixed point and is proportional to the displacement from the fixed points

1bii)
T=1.2secs
Log 1.2=0.079
0079 shown on graph with corresponding Log L read L correctly determined
===========================

NO 3 GRAPH


(3a)
TABULATE:
x(cm):10,20,30,40,50,60
V(v):0.65,0.75,1.00,1.20,1.45,1.55
I(A):0.20,0.30,0.35,0.40,0.45,0.55
LogV(v):-0.187,-0.125,0.000,0.079,0.161,0.190
LogI(ohm):-0.699,-0.523,-0.456,-0.396,-0.391,-0.360
SLOPE(s):=( LogI2-LOgI1)/(LogV2-LogV1)
=-0.2-(-0.7)/0.3-(-0.2)
=0.5/0.5
=1AV^-1

3axi)
i)ensured clean/tight terminals
ii)open key when reading was taken

3bi)As × increases the Brightness of the bulb increases, voltage and current through the bulb increases hence brightness increases.

3bii)Electrical device that do not obey ohm’s law are..:
¡)Diode
¡¡) capacitor
¡¡¡)transistor
¡v)thermistor
V)thyristor

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2 Comments on WAEC Physics Practical Answer – May/June 2017 Expo

  1. *1(a).*
    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

  2. The graphs are wrong oh……for the number 2 it must pass through the origin

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