NECO 2019 PHYSICS OBJ AND THEORY VERIFIED QUESTIONS AND ANSWER | EarlyAnswer, Best Waec, Neco Expo Site Runs

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Physic-Obj!

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Note; You Are Advice To Answer Question One (1) And Any Other Five (5) From Section A (Part I) And Four (4) From Section B. Enjoy

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(1a)

(pick 2)

(i) Solar Electric Power Generation

(ii) Solar Cooking

(iii) Solar Thermal Power Production

(iv) Solar-distillation

(1b)

Natural sattelite is a celestial body in space that orbits a larger body, such as Moon Which moves around the Earth.

Artificial satellite is a machine of human creation that is sent to the space or the orbit of the Earth for the collection of data, communication and other ends

(1c)

The applicable relationship is Ns/Np = Vs/Vp meaning the ratio of secondary voltage to primary voltage is equal to the ratio of secondary turns to primary turns

Ns = 200turns , Vs = 300V , Np = ? , Vp= 60V

Ns/Np=Vs/Vp

Np=Ns(Vp/Vs)

Np= 200 × (60/300)

Np = 200 × 0.2

Np= 40 turns

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(2a)

Force is an agent that changes or tends to change the state of rest or of uniform motion in a straight line of a body

(2b)

Contact force are forces which are in contact with the body to which they are applies while Field force are those forces whose sources do not require contact with the body to which the are applied

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(3a)

Maximum range (R) : Maximum range is defined as when the angle of the projection (?) is equal to 45° ie R = U^2sin90/g and ?=45°

R= U^2sin90/g and sin90=1

Rmax=U^2/g

(3b)

(i) Stable Equilibrium – A cone resting on its base

(ii) Unstable Equilibrium – A cone resting on its apex or vertex

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(4a)

It means that the glycerine which is in solid state will require a heat of 13°c to change to liquid state

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(4b)

The S.I unit of mass is in kilogram (kg) while that of weight is in Newton (N)

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(6)

Constructive interference is formed when the wave amplitudes reinforce each other, building a wave of even greater amplitude. Destructive interference is formed when the wave amplitudes oppose each other, resulting in waves of reduced amplitude.

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(7)

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(8a)

Faraday’s law states that the induced e.m.f. in a conducting circuit is directly proportional to the rate of change of magnetic flux linkage, ?, with the circuit.

(8b)

(i)Induction motors

(ii)Electric generators

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(9a)

Electric field acts on charges (Q) while Gravitational field acts on masses (m)

(9b)

Emf =12v

r =0.45?

R =5.0?

I =?

I =Emf/R+r

I =12/5+0.45=12/5.45

I =2.20A

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(11)

(Pick Only 1)

(i)it is used in generating heat energy required to generate electricity

(ii)it can be operated non-stop with the same nuclear capacity

(Pick Only 2)

(i)the plant set up is capital intensive

(ii)principal raw material (uranuim) is not easily available.

(iii)Careless exposure to raw material affects the cell tissues due to radiation effect.

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(12a)

Centripetal force and centrifugal force

(12b)

(12ci)

Achimede’s principle states that when a body is totally or partially immersed in a fluid, it experience an upthrust which is equal to the weight of the fluid displaced.

(12cii)

eo = 4×10^4 kg/m^3

Mo = 0.4kg

Vo = ?

eL = 1.2×10^2 kg/m^3

Where,

eo = Density of object

Mo = mass of object

Vo = volume of object

eo = Mo/Vo

Vo = Mo/eo = 0.4/4×10^4

Vo = 0.00001m^3

Mo in the liquid = eL × Vo

= 1.2×10^2 × Vo × 3/4

= (1.2×10^2 × 0.00001×3)/4

= 0.0009kg

= 9×10^-4 kg

Reading of the spring = 9×10^-4 ×10 = 9×10^-3 N

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(13a)

Examples of Renewable energy are :

(i) solar energy

(ii) Wind energy

(13b)

Radius of the wheel = B

Radius of the axle = O

V. R= Distance moved by effort/ Distance moved by load

Effort moves through a distance is equal to the circumference of the wheel 2?B and at the same time interval the load moves through the axle 2?D

V.R=2?B/2?D =B/D

(13ci)

It breaks because ice is less dense than water and water expands when it is frozen

(13cii)

Evaporation takes place at all temperature but boiling takes place at a particular temperature (100°c)

(13d)

m1=200kg

u1 = 16.7m/s

V2 = 0.5m/s

m2 = 200kg

m1u1 + m2V2 = (m1+m2)V

200×16.7 + 200×0.5 = (200+200)V

V = 3340+100/400 = 3440/400

V=8.6m/s

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(14ai)

A wave is a disturbance which travels through a medium transferring energy from one point to another without causing any permanent displacement of the medium

(14aii)

Tabulate

– Light wave

(i) It is an electromagnetic wave

(ii) It can be polarized

– Sound wave

(i) It is a mechanical wave

(ii) It can can not be polarized

(14b)

Long sight ( hypermetropia ) can be corrected with converging lens

(14c)

F= 440Hz

L1= 18.8cm

L2= 57.8cm

(14ci)

At resonance L+c= ?/4

Where C is the end correction. Assuming the end correction C is negligible,then

L1= ?/4

4L1=

4 × 18.8 = ?

4×18.8/100=0.752m

(14cii)

First position L1=?

Second position L2 =?

Hence, L2-L1 = ?/4

V= f? or f=V/?

V = 2f(L2-L1)

V= 2×440( 0.5733 – 0.188)

V= 880(0.385)

V=338.8m/s

(14ciii)

Overtime = 5?/4

5×0.752/4

= 3.76/4

= 0.94m or 94cm

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(15a)

Electric field intensity is the measure of intensity or strength of electrical force per unit charge at any given point in the electric field. It is denoted by the letter E and its Unit is Newton per Coulomb (N/C). Where

F is force (N)

Q is Change (C)

(15bi)

A lead accumulator in charged by passing direct current (d.c) through it in the opposite direction to that which its supplies. The positive terminal of the d.c is connected to the positive terminal of the lead accumulator and the negative terminal of the d.c is connected to the negative terminal of the accumulator.

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(15bii)

Electrolyte in battery os a solution of SO? and H²O and over time can be lost by slight spills and evaporation and using distilled water it is free from additional minerals that can be find in tap water and these minerals can significantly decrease in life of batteries

(15ci)

Faraday’s law of electrolysis ; that the chemical deposition due to the flow of current through an electrolyte is directly proportional to the quantity of electricity (coulombs) passed through it. i.e. mass of chemical deposition.

(15cii)

Area = 50cm² => 5*10-³ M²

I = 7A

t = 45*60(s)

T = thickness

M = z i t

m = 3.3 *10^-7 *7845*60

=>6.237 * 10-³ kg

P=m/v

8.9 * 10³kg/m³ = 6.237 * 10-³/V

V = 6.237 * 10-³/8.9 * 10³

=> 7.008*10 -> m³

Thickness = volume/area

7.008*10^-7/5*10-³

=> 1.40*10-?m

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(16ai)

Binding energy is the minimum energy or work required to separate the nucleons of an atom

(16aii)

(i)it is used in medicine as a radiotherapy

(ii)it is used in industry to study the defects in metals and welded joints

(16bi)

The intensity of x- ray can be increased in x- ray tube by increasing the voltage which results to an increase intensity of an electron

(16bii)

(i)both are electromagnetic waves

(ii) Both are high energy photography

(16ci)

W=2.25*10^-19J

?=3.0*10^-7m

fo=?

W= hfo

2.25*10^-19 = 6.6 *10^34fo

fo= 2.25*10 ^-19/6.6*10^-34

= 2.25/6.6 *10 ^-19 +34

=0.341*10^15Hz

=3.41*10^14Hz

(16cii)

Max energy liberated = E=hc/? – W

= (6.6×10^-34 × 3×10^8/3.0×10^-7) – 2.28×10^-19

(6.6×10^-19) – (2.25×10^-19)

= 4.35×10^-19 J

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Posted by on 13th June 2019.

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