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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

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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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3 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. I need answers for physics practical

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

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