Waec 2017 PHYSICS Obj And Theory Answers – May/June Expo

PHYSICS OBJ
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1)decrease in height (h)
increase in time (t)
this shows that distance changes with time
2)given that U=15m3^-1
R=U* sqr2h/g
h=20m
g=10
R=15*sqr2*20/10
R=15*sqr40/10
R=15*sqr4
R=15*2=30m
R=30m
3i) Brownian Motion
II) Atomic Size
Iii) Expansion
4) Let the unstrength legth be Lo
Using F=Ke
I.e. F/e=K
F1/e1=F2/e2=k
4/14-Lo=6/4
6(14-Lo)=16
84-6Lo=16
84-16=6Lo
6Lo=68
Lo=68/16
Lo=11.33cm
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5a)
i)force
ii)length
5b)
By increasing the density mosquitoes lavrva than the density
of water
================
6i)Energy efficient- so far the best light for interior lighting.I
ii)Low production cost (of tubes, not of the ballasts)
iii)Long life of tubes.
================
7)
i)It requires low voltage sources for it to function
ii)It cannot be easily broken
iii)It is cheaper and quite easy to manufacture
================
8a) It is a straight line graph
II) The gradient is the velocity
8b)If their distance and masses are doubled their
corresponding force would also be doubled and the work
done respectively
I.e.Workdone=Force * distance
Force= Mass * Acceleration
W= Mg * d
|
Increase
8c) -Acceleration due to gravity
– At maximum height, final velocity is zero
8d (i)pushing someone on a swing.
(ii)Tuning a radio to a particular frequency.
================================
10a) A wave front is an imaginary surface passing through
the points of a medium oscillatory in phase
10bi)Prismatic binoculars is used to see round corners
II) Prism Periscope is used to bend and reflect light
10bii)i) Refractive index of the glass prism
II) The angle of the incident of ray
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11a A dielectric is an electrical insulator that can be polorised
by an applied electric field.
11aii) GIVEN: A = 9.6 * 10^-3 M^2
d = 2.25 * 10^4
Eo = 8.85 * 10^-12 F/m
Er = 900
C = /
using; C = EoErA/d
capacity, C = 8.85*10^-12 * 900 * 9.6*10^-3/2.25 * 106-4
C = 33984 * 10^-11
C = 3.3984 8 10^7 F
C =0.344F
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12ai)Nuclear fission is a nuclear reaction in which a heavy
nucleus splits spontaneously or on impact with another
particle, with the release of energy.
12aii)a)A graphite reactor is a nuclear reactor that uses
carbon as a neutron moderator, which allows un-enriched
uranium to be used as nuclear fuel.
12aii)b)Boron rods are used in
nuclear reactors to control the fission rate of uranium and
plutonium. They are composed of chemical elements such
as boron, silver, indium and cadmium that are capable of
absorbing many neutrons without themselves fissioning.

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