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## Neco 2018 Physics Theory and Objective Answers

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Neco 2018 Physics Theory and Objective Answers by : 1:00 am On June 14, 2018

Neco 2018 Physics Theory and Obj Answers

Physics OBJ:
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21EEACBAECAB
31EAAECEECBD
41AECCABEECE
51CEABBCABEB
Pease NOTE: You Are To Answer Six(6) QUESTION In Section A
While Four (4) QUESTIONS In Section B
1a)
water passes through a dam, and into a river below. The more water that
passes through a dam, the more energy is produced. Once a dam is
built, an artificial man-made lake is created behind the dam. Electricity
is produced by a device called a turbine. Turbines contain metal coils
surrounded by magnets. When the magnets spin over the metal coils,
electricity is produced. Turbines are located inside dams. The falling
water spins the magnets.
1b)
Given:
M=10
U=?
V=mu
F=+5cm
V=10u(virtual image)
using the real is positive convention
1/f=1/u+1/v
1/5=1/u-1/10u
1/5=10-1/10u
1/5=9/10u
10u=45
u=45/10
u=4.5cm
the object must be placed 4.5cm from the microscope.
2)
the distance covered S by a body with initail speed U and final speed V
in time t is
distance = average speed x time
S = (u+v/2)t
first equation
acceleration = change in velocity/time
a=v-u/t
v-u=at
v=u+at
putting the first equation into S = (u+v/2)t we have
S = (u+u+at/2)t
S = (2u+at/2)t
S = (u+at/2/2)t
S = ut+1/2at^2
this is the second equation
6a)
the incident ray, the reflected ray and the normal at the point of
incidence all lie in the same plane
6b)
i)diverging lens
ii)the diverge light rays entering the eye from a distance object and
make them appear to be coming from the person far point
7a)
ii)used as a shaving mirror
given
object distance U =13cm
image distance V = -4cm
focal length F = ?
Using the real is positive convention
1/f=1/u+1/v
1/f=1/13-1/4
1/f=4-13/52
1/f= -9/52
f= -52/9= -5.8cm
9a)
i)cross sectional area of plates
ii)distanace between plates
9b)
Given:
M=6kg
D=3m
G=6.6710^-11 Nm^2kg^-2
using:
F= Gm^2/d^2
F= 6.667
10^-116^2/3^2
F= 2.668
10^-10N
10a)
i)Mercury dropped on glass from droplets because the cohesion of
mercury is stronger than it adhesion
ii)Water rise in capillary tube because the force of adhesion at water
molecules with glass is greater than their cohesion to each other.
10b)
Surface tension, the ability of water to behave an elastic skin make it
possible for an insect to crawl on water
12ai)
A trajectory is the path traced by a projectile
12aii)
I)the fired bullet
ii)thrown javelin
iii)thrown bomb
12b)
i)A scalar quantity has no direction while vector quantity has direction
ii)Scalars can be added and subtracted easily by using ordinary algebra
while vector quantity however have to be added or subtracted by vector
diagrams and law like parallelogram,triangle law and resolution of
vectors.
12ci)
12cii)
I) from the diagram
slope Bc = CD/BD
14=(V-20)/20
V-20=280
V=280+20
Final velocity V=300mls
II)Total distance= Area of rectangle OABFO+Area Of Trapezium FBCEF
=(OAOF) + [1/2(BF+CE)FE] =(2040) + [1/2(20+300)20] =800+3200
=400metres
14a)
The law of reflection state that the angle which the incident ray makes
with the normal is equal to the angle which the reflected ray makes to
the same normal.
14b)
i)Effect of density
ii)Effect of temperature:- In a gas.
14c)
14d)
using the lens formula
1/f=1/u+1/v
1/5=1/6+1/v
1/5-1/6=1/v
6-5/30=1/v
1/30=1/v
V=30cm (image distance from lens)
Total distance between image of len And image of mirror is
=30+12+16
=48cm
13a)
Specific heat capacity can be defined as the quantity of heat required to
raise a unit mass of a material by one kelvin(k) or degrees Celsius('C)
13aii)
i)change in temperature of phase/State
ii)Change in resistance and in colour.
13aiii)
i)Linear) colour.
13aiii)
i)Linear) expansivity results to expansion of metals or concrete bridges.
ii)It as well causes cracking of glass cup when hot water is poured into
the glass cup.
13b)
i)Heat is nothing but the amount of energy in a body. As against this,
temperature is something that measures the intensity of heat.
ii)Heat measures both kinetic and potential energy contained by
molecules in an object. On the other hand, temperature measures
average kinetic energy of molecules in substance.
iii)The main feature of heat is that it travels from hotter region to
cooler region. Unlike temperature, which rises when heated and falls
when cooled.
13ci)
when an inflated ballon is pierced and eleased, it obeys newton's third
law of motion. Air rushes out from the pierced hole and the balloon
moves in the opposite direction
13cii)
Jet
13d)
using [email protected] [email protected]
Given [email protected] [email protected]=(25-20)=5degree
Cx=1/2CY
then Mx[1/2CY]=MYCY
Mx/My=Cy/1/2Cy
Mx/My=2
Ratio of mass Of X to Y is 2:1
15ai)
Force field is a region around a body in which it experiences an effect
(force) due to the presence of another body
15aii)
i)gravitational field
ii)magnetic field
15b)
Show that the escape velocity(Ve) of an object from the earth surface is
√2Gme/r
To prove the escape velocity (Ve) of an object from the earth surface we
can say let the kinetic energy of the object of mass M is
Ek=1/2MVe^2
When an object is at any given point P which is at a distance X from the
centre of the earth the force of unity between the object and earth is
F=Gmm/X^2
Work done is taken the body against gravitational attraction
DW=Fdx=Gmm/X^2 DX
Where W=work done in taking the body against gravitational attraction
W={R DW= {R Gmm/X^2 DM
=Gmm {R X^2 DM = Gmm [X^2/Y {R
= -Gmm [1/X]R = - Gmm [1/~ - 1/R] Or, W=Gmm/R
For the object to escape from the earth surface
Ek=workdone,W
Ek=W
1/2MVe=Gmm/R
Ve=√2Gm/R(proved)
15ci)
i)Power supply smoothing applications
ii)RF coupling or filter capacitor applications
15cii)
Data given
d =4mm=410^-3 , 0.004m
A= 0.2m^2, V=300V
[Eo=8.85
10^-12fm^-1] i)capacitance of the capacitor
using the approprate formula
C=EoAv/d
C=8.8510^-120.2200/0.004
C=8.85
10^-12210^-1210^2/410^3
C= 35.4
10^-11/410^-3
C= 8.85
10^-10^-11+3
C=8.8510^-8F
the capacitance of the capacitor is 8.85
10^-8F
ii)Electric Field intensity between the plates
E=F/q =K.q.d/d^2/q
E=kQ/d^2
E=8.8510^-12Q/d^2
but Q=CV
Q=8.8510^-8210^2
Q=17.7
10^-6 C,1.7710^-7C
E=8.85
10^-121.7710^-7/(410^-3)^2
E=15.7
10^-19/1610^-6
E=1.57
10^-20/1.610^-5
E=0.98
10^-15
E=9.810^-110^-15
E=9.810^-16N|C or E=9.810^-16NC
the electric field intensity have the plates is 9.810^-16 NC
17a)
i)Stay on top of large machinery operator training
ii)Keep large machinery clean, and maintain a clean environment
17bi)
-Compound Microsoft-
for viewing samples at high magnification (40 - 1000x), which is
achieved by the combined effect of two sets of lenses: the ocular lens
(in the eyepiece) and the objective lenses
17bii)
-Film projector-
an optical device that projects an image (or moving images) onto a
surface, commonly a projection screen.
17c)
Artificial satellite orbits the earth and observes it. A rocket is designed
to go to different planets, either taking people with it, or taking a space
prob to take pictures of that planet.
17d)
data given
Rg=5n,Ig=10mA Vg=40V Rx=?
Ig=10mA =10
10^-3A
Ig=10^-2A
For Conversion Of galvanometer into voltmeter.
Vg=Ig(Rg+Rx)
Vg=Ig Rg + Ig Rx
Vg-Ig Rg =Ig Rx
Rx=Vg-IgRg/Ig
Rx=Vg/Ig-Rg
=40/10^-2 - 5/1
Rx=40/0.01 - 5/1
Rx=40-0.05/0.01
Rx=39.95/0.01
Rx=3995
the resistance of resistor is 3995

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Physics obj
1-10 CEABCBAABB
11-20 DCCBCBCCAE
21-30 BECDDBEDDE
41-50 CBDCBBBDCB
51-60 CEDDCBAEAA

1ai)
– The body tube
– The launch lug
1aii)
– Internet and multimedia: This involves communication and exchange of information through the internet
1b)
Given:
object distance for eyepiece, u=3.0cm
Final image distance v=?
Focal length of eyepiece f=5cm
Using mirror/lens formular
1/f=1/u+12/v
1/5=1/3+1/v
Multiply through by 15v
3v=5v+15
3v-5v=15
-2v=15
v=15/-2
v=-7.5cm
The image is virtual and 7.5cm from the eyepiece on the same side of the eyepiece as the object

3a)
-Book lying on table
-A car engine that keeps running for a constant for a considerable length of time
3aii)
-Rolling ball
-Pendulum ball
3b)
Ship floats in water,although they are made of steel and iron which are materials denser than water. This Is because the ship is hollow I.e an open object

4a)
Specific latent heat of vaporization ( L ) of a substance is the quantity of heat required to change unit mass of the substance from it’s liquid at boiling point to vapor without a change in temperature
4b)
– Kinetic energy is the energy due to motion while potential energy is the energy at rest due to it’s level or position
– kinetic energy is an horizontal energy while potential energy is a vertical energy
– Kinetic energy is denoted by k.E while potential energy is denoted by P.E
– Kinetic energy does not act against gravity while potential energy acts against gravity

6a)
Wave front is a line or surface in the path of advancing wave on which all d particles are in the same phase or state of disturbance
6b)
-Plane wave front
– Spherical or circular wave front

7)
– Pupil:The pupil serves as the passage for light into the eye
– Shutter:The Shutter works on the s*********n of light before photograph can be taken
-Screen of pinhole camera: It helps to form images which are inverted

PART II
12ai) Newton’s second law of motion states that the rate of change of momentum is proportional to the impressed fotvr and takes place in the direction of the force
12aii)
– The motion of the strings in a musical instrument eg. Guitar
– The motion of the balance wheel of a w***h
12bi)
Resultant force is that single force which acting alone will have the same effect in magnitude and direction as two or more forces acting together
12bii)
Equilbrum force is that single force which will balance all the other forces taken together. It is equal in magnitude buy opposite in direction to the resultant force
12ci)
Resultant force F =root4^2 + 3^2
F =root16 + 9
F =root25
F=5N
12cii)
Using F = m(v – u) / t
5= 5.5 (v – 2) / (5 × 60)
=5 × 60×5 = 5.5(V-2)
5.5(V – 2) = 1500
V – 2 = 272.7
V=272.7 + 2
V=274.7m/s
Final velocity of body is = 274.7m/s

13ai)
– Solar energy is for providing a cheap and clean source of hot water supply.
– Solar energy provides electricity supply
13aii)
-Renewable energy are those that can be replaced as they are used up. They can be continually replenished as they are exploited and utilized while Non-Renewable energy are those that cannot be replenished as they are used up
-Examples of renewable energy are Solar energy, wind energy, Biomass and Bio feuls while examples of Non renewable energy are Coal and wood, Fossil fuel, Petroleum and Natural gas, Nuclear energy
13b)
The principle of conservation of linear momentum us also utilized in the propulsion of jet aircraft. Gases are burnt within the combustion chambers of the engine. As jets of hot gases are expelled downwards through the tail nozzle at very high speeds from the aircraft, an equal and opposite momentum is given to the rocket or aircraft which then moves forward
13c)
Given:
mass m=0.2kg
Heat lost H=4200J
Initial temperature tita1=100C
Final temperature tita2=?
SHC of water Cw=4200j/kg/k
Using:
Heat lost=MwCw(tita1-tita2)
4200=0.24200(100-tita2)
(100-tita2)=4200/(0,2*4200)
100-tita2=5
tita2=100-5
tita2=95C
Final temperature=95C

14ai)
A transverse wave is one which travels perpendicularly to the direction of vibrations producing the wave
14aii)
-Light waves do not need a material medium for its propagation but sound waves does
-Light waves cannot be plane polarized but sound waves can
14b)
Given y=4sin(1000piet/landa + 0.5x)
Comparing with y=Asin(2pie ft +2pie/landax)
(i) 2pie/landa=0.5
landa=2pie/0.5
landa=2
3.142/0.5
landa=12.56cm
Hence wavelength, landa=12.56cm
(ii)Also 1000pie/2pie*landa=500/landa
=500/12.56
=39.8Hz
f=39.8Hz
(iii)Speed V=flanda
v=500/12.56 *12.56
Speed v=500cm/s
v=5m/s

15a)
Coulomb’s law state that magnitude of the electrostatic force of attraction between two point charges is directly proportional to the product of the magnitudes of the charges and inversely proportional to the square of the distance between them
15bi)
Diagram
15bii)
Let equivalent resistance be R
1/R = 1/R1 + 1/R2 + 1/R3
I/R = R2R3 + R1R3 + R1R2 / R1R2R3
R= R1R2R3 / R1R2+R2R3+R1R3
15c)
Given:
200Ω C =4mf f=50h2 π =3.14
Impedance Z =√R^2 + (1/2Ω + c) ^2
Z =√200^2 + (1/2×3.145×50×4×10^-6)^2
Z=√200^2 + 796.178^2
Z=√40000 + 633900
Z=√673900
Z=821Ω

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