# PHYSICS OBJ AND ESSAY THEORY NECO 2020 QUESTIONS AND ANSWERS

PHYSICS OBJ AND ESSAY THEORY NECO 2020 QUESTIONS AND ANSWERS

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Monday 23rd November 2020

Paper III & II: Objective & Essay – Physics
10:00am – 1:00pm

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*NECO 2020 PHYSICS OBJ*
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*NECO 2020 SECTION A*

*ANSWERS ONLY 6 FROM THIS SECTION NUMBER 1 IS COMPULSORY*
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PART I

(1a)
(i)printing machine
(ii)sterilizer

(1b)
Diagram (step up transformer)

SEE DIAGRAM

(1c)
1=1.26
t=48005
m=?
z=3.3*10^-⁴g
m=3.3*10^-⁴*1.26*4500
=1.996gram
≅2gram
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(2a)
A system is unstable when displaced, it experiences a net force in the same direction as the displacement from equilibrium. It tends to accelerate away from its equilibrium position if displaced even slightly while for neutral equilibrium, the system is independent of displacement from its original position

SEE DIAGRAM

(2b)
(ii)Low centre of gravity
(ii)Large surface area in contact
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(3a)
Velocity is defined as the rate of change in the displacement of a body it is a vector quantity with the S.I unit of ms-¹

(3b)
DIAGRAM
SEE DIAGRAM
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(4)
At equilibrium position Point B, the body possess maxim kinetic energy. As it moves out to end point A and C. It stops momentarily before changing its direction.

(Diagram)
SEE DIAGRAM
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(5a)
They are both derived quantities

(Diagram)

SEE DIAGRAM

(5b)
67-0/100-0 = x-25/100-25
67/100 = x-25/75
61*3 = 4(x-25)
201 = 4x-100
4x = 201+100
4x = 301
x = 301/4 = 75.25 ohms
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(6a)
(i)violin
(ii)guitar

(6b)
The depth of field of a lens camera is less than that of a pinhole camera
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(7a)
– An amplifier
– A speaker

(7b)
u = 16cm
m = 4=v/u
:. v =4u
v = 4×16 = 64cm
Recall, 1/f = 1/u + 1/v
1/f = 1/16 + 1/64
1/f = 4+1/64
1/f = 5/64
f = 64/5 = 12.8cm
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(8a)
The zinc atoms on the surface of the anode oxidizes I;e they give up both their valence electrons to become positively

(8b)
Diagram
SEE DIAGRAM
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(9a)
The power factor of a circuit is unity when the apparent power equals or some as the real power

(9b)
V=Vr+Vc
15=12+Vc
Vc=15-12
Vc=3v
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(10a)
(i)Viscosity
(ii)weight
(iii)upthrust

(10bi)
(i)Viscosity; the force in between the layers of flurds this force would tend to reduce the velocity at which the stone moves down till it reach terminal velocity

(ii)weight; is the actual force acting of the stone in the liquid.

(iii)upthrust; is the upward force felt by reply objects in flurd, due to the area displace
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(11i)
A=9 (molecular mass)
B=6 (atomic mass)
C=0

(11ii)
Z=Energy

(11iii)
Nuclear fusion
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