Get 2020 Waec Gce Physics Obj and theory Questions and Answers Hours To Exam

2020 Waec Gce Physics Obj and theory
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Physic-Ob!
1. Gravitational force
2. Kinetic or potential
3. Violet
4. Tesla
5. Electric motor
6. Loudness
7. Electric field
8. Constriction
9. Lead
10. Good absorbers of radiant heat are good emitters
11. Decrease
12. Sound wave
13. [img]https://i.imgur.com/GRHScLd.jpg[/img]
14 I and IV only
15. Diaphragm
16. Multiplier is high resistance change it to voltmeter
17. P is at the level with Q
18. 34.0⁰C
19. 0.02secs
20. 2.7*10kg/m³
21. Centripetal force applied in the wheel rotates it
22. Mg(sθ-μcosθ)
23.0.60Ω^-¹m^-¹
24. 800N
25. Both earth and Moon travel around the sun
26. 0.04secs
27. 0.25*10³Ω
28. 2uf
29. Radiate specific values of energy of electromagnetic waves
30. 6m/s²
31. 0.67
32. Axe
33. Mass of the conductor
34. 20ms^-¹
35. Charge ionises the sorrounding air
36. East west
37. 33.3A
38. 27.8m
39. 17N
40. 40g
41. Critical angle
42. Momentum
43. Mixture of gases
44. J
45. Jumps to a higher permissible energy level
46. Mass of the liquid
47. Spring balance
48. Argon
49. Images are formed behind the mirror always
50. Charles coloumb

The End Of Wahala Waec Gce Physics Obj.
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PART I
ANSWER FIVE (5) ONLY.
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(1)
(i)They are use to find the unit of a given physical quantity in a given system of units.
(ii)They are use to find dimensions of physical constants or coefficients.
(iii)They are use to convert a physical quantity from one system of units to another.
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(2a)
Time of flight: Time of flight (T) is the time required for a projectile to return to the Same level from which it was projected
T= 2usin θ / g

(2b)
Maximum height: Maximum height(H) is the highest vertical distance attained as measured from the horizontal projectile plane.
H = U²sin²θ / 2g

(2c)
Range : Range(R) is defined as the horizontal distance from the point of projection to the point where the projectile hits the projection plane again
R= U²sin2θ / g
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(5a)
Forbidden gap is the group of energy levels that cannot be occupied by the electrons, these energies lies in between conduction band and valence band.

(5b)
(i) free electrons which have negative charges
(ii) holes, which have positive charges

=================
(6)
Me = 9.1*10-³¹kg
V = 1.0*10⁶m/s
h = 6.6*10-³⁴Js
λ = h/MeV
λ = 6.6*10-³⁴/9.1*10-³¹*1.0*10⁶
= 0.7252*10-⁹
λ = 7.25*10-¹⁰m

====================

(7a)
Magnetic materials are materials studied and used mainly for their magnetic properties. The magnetic response of a materials is largely determined by the magnetic dipole moment associated with the intrinsic angular momentum, or spin, of its electrons.

(7b)
(i)by heating past the Curie point
(ii)by applying a strong magnetic field
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PART II
ANSWER 3 ONLY.
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(8ai)
Work is said to be done whenever a force moves a body through a certain distance in the direction of force and is equal to the product of the force and the distance moved.

(8aii)
Workdone = Force * distance
= F*S
F = m(v/t)
Workdone = m(v/t) * 1/2vt
= 1/2mv²
Ek = 1/2mv²
ie workdone = change in kinetic energy of the body

(8bi)
Kinetic friction is the force that must be overcome so that a body can move with uniform speed over another body

(8bii)
(i)Nature of surfaces in contact
(ii)Depends on the normal force pressing the surfaces together

(8ci)
Tc – umg = ma
Tc – (0.3 * 3* 10)= 3*2
Tc – 9 = 6
Tc = 9+6 = 15N

(8cii)
TB – 2umg = ma
TB – 2(9)= 3*2
TB = 6+18
TB = 24N

(8ciii)
TA – 3umg = ma
TA – 3(9) = 3*2
TA – 27 = 6
TA = 6+27
TA = 33N

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(9ai)
Heat describes the transfer of thermal energy between molecules within a system and is measured in Joules. Heat measures how energy moves or flows. … Temperature describes the average kinetic energy of molecules within a material or system and is measured in Celsius (°C), Kelvin(K), Fahrenheit (°F), or Rankine (R).

(9aii)
The lower fixed point, or ice point, is the temperature of pure melting ice at normal atmospheric pressure. While The upper fixed point, is the temperature of pure boiling water at normal atmospheric pressure.

(9bi)
Kink or construction

(9bii)
Fine narrowbore

(9biii)
Thing glass tube or bulb

(9ci)
Linear expansivity is the fractional increase in length of a specimen of a solid, per unit rise in temperature. If a specimen increases in length from l1 to l2 when its temperature is raised θ°, then the expansivity (α) is given by: l2 = l1(1 + αθ).

(9cii)
Let initial length of brass rod be Lbo
Let initial length of iron rod be Lio
At 20⁰C , Lbo – Lio = 28cm
At 90⁰C, Lb = Lbo( 1*∝b∆∅)= Lbo( 1+0.00133)
Li = Lio( 1+∝i∆∅) = Lio(1+0.00084)
Lb – Li = 28cm
1.00133Lbo – 1.00084Lio = 28
ie 1.00133Lbo – 1.00084Lio = Lbo – Lio
Lio – 1.00084 = 1.00133 – Lbo
1.00084Lio = 1.00133Lbo
Lio = (1.00133/1.00084)Lbo
Lio = (133/84)Lbo
Initial length of iron rod = 133/84 of initial length of brass rod
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(10bi)
The principle of superposition says: When two or more waves cross at a point, the displacement at that point is equal to the sum of the displacements of the individual waves. The individual wave displacements may be positive or negative. If the displacements are vectors, then the sum is calculated by vector addition.

(10c)
Refraction depends on the wavelength. As blue light has shorter wavelength moving from air to glass than red so it refract more than red.
(11ai)
Reactance is the opposition of a circuit element to the flow of current due to that element’s inductance or capacitance.

(11aii)
Impedance is measure of the opposition to the flow of alternating current through a circuit

(11bi)
Half-life, in radioactivity; is the interval of time required for one-half of the atomic nuclei of a radioactive sample to decay (change spontaneously into other nuclear species by emitting particles and energy), or, equivalently, the time interval required for the number of disintegrations per second of a radioactive.

(11bii)
Quality of sound is determined by overtone.

(11c)
Donor Impurity; is a dopant having 5 electrons in its valence shell when doped with a semiconductor to increase its conductivity is known as a donor impurity. In other words It holds the ability to donate an extra electron present in its valence shell to the neighbouring atom.