2018 WAEC GCE PHYSICS OBJECTIVE & ESSAY ANSWER NOW AVAILABLE.

(1a)
Young modulus of a material or the modulus of
elasticity.

(1b)
Potential Energy to kinetic Energy.

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(2)
e = 0.7m
m=60 × 10^-3kg = 6.0×10^-2kg
K = 200Nm^-1
W = 1/2ke² = 1/2mv²
1/2ke² = 1/2mv²
V² = ke²/m = 200×0.7²/6.0×10^-2
V² = 98×10²/6
V² = 16.33×10²
V = √1633
V = 40.4
Speed = 40.4ms^-1

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(3)
(i) Optical fibres have extremely high bandwidth
(ii) They have longer transmission distance
(iii) They have resistance to electromagnetic
interference

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(4a)
It is used in geometric stations used to move a
satellite from low earth orbit into a
geostationary orbit.

(4b)
Polar orbit satellite is used in earth mapping.

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(5a)
(i) Centripetal force
(ii) Centrifugal force

(5b)
Ft = mDv
where F = force
t = time
Dv = change in velocity
m = mass of object
Hence F = mDv/t

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(6a)
(i) It can cause short and long term sun burn
effects.
(ii)It can cause blindness when flashed to the
eyes.

(6b) Energy = hf
= 6.60×10^-34 × 4.82×10^14
= 3.18×10^-19J
= 1.99ev

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(7)
V = 2πR/T
R = 9.6×10^6 + 6.4×10^6 =16×10^6 m
T = 24hrs =(24×60×60)s
V = 2×3.142×16×10^6/24×60×60
V = 1162.96m/s

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8a) Mass is the amount of material contained in a body and the SI unit is Kg while Weight is the force exerted on a body by the gravity of the object. ..Mass is a scalar quantity( It has not specific direction), While Foce is a vector quantity (Its in the same direction with gravity)

8ai)
Mass is measured in Kg
Weight is measured in Newton
Mass is a scalar quantity
Weight is a vector quantity
Mass is constant
Weight varies

8aii) Clockwise moment about the pivot.
Moment = Force x Distance
Moment = 250 x 0.75
Moment = 187.5Nm

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(11a)
Lenz’s law states that an induced current is in
such direction that it’s magnetic effect opposes
the change by which the current is induced.

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(11b)
(i) Magnets are used in construction of
speakers.
(ii) They are used to store data in computers.
(iii) Used in magnetic resonance imaging
machines.

(11ci)
(a) Two coils: So as to produce an induced
current from one coil to the other.
(b) an iron core: To increase the strength of the
magnetic field.

(11cii)

(11d)
Total resistance in series
Rt = R1 + R2
= 500 + 400
Rt = 900ohms

Taking E = 6v
E = V + ir
E = VR + Ir
E = I ( R + r)
I = E/R + r

taking r = 200ohms
I = 6/900+200
I = 6/1100
I = 0.005A

Hence the voltmeter reading
V = IR
= 0.005 × 200
= 1.09v
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