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WAEC 2018 PHYSICS Practical Questions and Answers/Expo/Dubs/Runs
2018 WAEC MAY/JUNE PHYSICS PRACTICAL ANSWERS
PHYSICS PRACTICAL THEORY:
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(1a)
TABULATE:
S/N: 1, 2 , 3, 4, 5
L(cm): 90.00, 80.00, 70.00, 60.00, 50.00
T(s): 38.00, 36.00, 34.00, 31.00, 28.00
T = t/20(sqt): 1.90, 1.80, 1.70, 1.55, 1.40
√L(cm^1/2): 9.49, 8.94, 8.37, 7.73, 7.07
(1aix)
Slope(s) = Δvertical/Δhorizontal
=1.90 – 1.55/9.49 – 7.75
= 0.35/1.74
S = 0.201
(1ax)
g = 4π²/S²
= 4 ×(3.142)²/(0.201)²
= 977.4cm/s²
(1axi)
(i) I ensured the angle of oscillation is relatively small.
(ii) I ensured that no external force is added to the system of oscillation.
(iii) I ensured the oscillation is perfect
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2ai)
fo=15cm
2av)
a=60.00cm
b=20.00cm
Hence L=a/b=60.00/20.00
L=3
2avi)
TABULATE
S/N:1,2,3,4,5
b(cm):20.00,25.00,35.00,40.00
a(cm):60.00,37.50,30.00,26.25,24.00
L=a/b:3.00,1.50,1.00,0.75,0.60
2avii)
Slope=Change in L/Change in a
=(3-0.25)/(60-18.6)
=2.75/41.4
=0.006642
2aviii)
S^-1=1/S
=(1/0.0066425cm)
S=15.05
S=15cm
2aix)
PRECAUTIONS
-I ensured that all apparatus are in straight line
-I avoided error due to parallax when reading the metre rule
-I avoided zero error on the metre rule
2bi)
u=10cm
f=15cm
Using 1/v+1/u=1/f
1/f-1/u=1/v
1/v=1/15-1/10
1/v=(2-3)/30
1/v=-1/30
v=-30cm
The characteristics of image formed are:
-It is virtual
-It is enlarged and magnified ie twice or two times as big as the object m=2
2bii)
The concave mirror mounted in its holder is moved to and fro in front of the screen until a sharp image of the cross wire of the ray box is formed on the screen adjacent of the object.The distance between the mirror and the screen was measured as 30cm since the radius of curvature r=2fo then half is distance
2bi)
he characteristics of imaged formed are :
i)It is virtual
ii) It is enlarged or magnified i.e. twice or two times bigger as the object(m=2)
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(3a)
TABULATE
S/N:1,2,3,4,5
d(cm):25.00,35.00,50.00,65.00,80.00
I(A):0.80,0.75,0.65,0.60
I^-1(A^-1):1.2500,1.3333,1.4286,1.5385,1.6667
(3aviii)
Slope= Change in logI^-1/Change in d(cm)
(Y2-Y1)/(X2-X1)=(0.23-0.06)/(80.0-13.0)
=0.17/67=0.0025
S=0.0025
(3aix)
-I ensure tight connections
-I avoided zero error of the ammeter
(3bii)
-Length of the wire
-temperature
-cross sectional area
-Nature of the material
3 )
– precautions –
take any two
i ) I removed key when reading is not taking
ii ) I ensured tight connections at the terminals
iii ) I avoided parallax error when taking reading from the ammeter.
