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Physics
WAEC / WASSCE 2020
Mechanics and Properties of Matter
Solution
You are provided with a resistance box R, voltmeter, key, cell of e.m.f. E, constantan wire, standard resistor, RX, an ammeter, and other necessary apparatus.
(i) Measure and record the e.m.f. E of the cell provided.
(ii) Set up the circuit as shown in the diagram above.
(iii) Set R to 1\(\Omega\). Close the key, read and record the current I and the corresponding voltage V.
(iv) Repeat the procedure for four other values of R= 2\(\Omega\), 4\(\Omega, 6\(\Omega\), and 8\(\Omega\).
(v) In each case, read and record I and V.
(vi) Tabulate the reading.
(vii) Plot a graph of V on the vertical axis and I on the horizontal axis.
(viii) Determine the slope s, of the graph.
(ix) State two precautions are taken to ensure accurate results
(b) )State two advantages of connecting identical cells in parallel.
(ii) State two factors to consider in choosing the material for the design of a resistor
medium Difficulty
Verified Correct Answer: Option
Physical Principles & Numerical Solution
R(n)
I(A)
V(v)
1.0
2.0
4.0
6.0
8.0
0.40
0.35
0.28
0.22
0.18
0.65
0.58
0.22
0.45
0.40
E = 3.00v
(x) Precautions:
- Key opened in between readings/key opened when readings were not taken
- Ensuring tight connections Avoid parallax error when taking a reading on voltmeter/ammeter Repeated readings (shown on the table)
- Noted/corrected zero error on voltmetre/ammeter
- Clean terminals ensured
(b)Advantages of connecting identical cells in parallel produce a larger amount of current. supply steady current for a long period - efficiency is high
(ii) Factors to consider in choosing a material for the design of a resistor
- Power rating-Tolerance
- Voltage rating
-Temperature coefficient
- Noise
- Frequency response
- Stability
- Resistivity
Source: Myschool Past Questions Archive (Record #59755)
Physics
UTME / JAMB 2020
Heat Energy & Temperature
Solution
A substance has half of 3 min. After 6 min, the count rate was observed to be 400. What was its count rate at zero time?
A
1600
B
1200
C
200
D
2400
medium Difficulty
Verified Correct Answer: Option A
Physical Principles & Numerical Solution
Let the count rate at zero time be N
N \(\frac{3 min}{\to}\) \(\frac{N}{2}\) \(\frac{3 min}{\to}\) \(\frac{N}{4}\)
\(\frac{N}{4}\)
= 400
N = \(\frac{400}{N/4}\) x N
= 1600
Source: Official Exam / Past Question Archive
Physics
WAEC / WASSCE 2020
Heat Energy & Temperature
Solution
You are provided with a resistance box R, voltmeter, key, cell of e.m.f. E, constantan wire, standard resistor, RX, an ammeter, and other necessary apparatus.
(i) Measure and record the e.m.f. E of the cell provided.
(ii) Set up the circuit as shown in the diagram above.
(iii) Set R to 1\(\Omega\). Close the key, read and record the current I and the corresponding voltage V.
(iv) Repeat the procedure for four other values of R= 2\(\Omega\), 4\(\Omega, 6\(\Omega\), and 8\(\Omega\).
(v) In each case, read and record I and V.
(vi) Tabulate the reading.
(vii) Plot a graph of V on the vertical axis and I on the horizontal axis.
(viii) Determine the slope s, of the graph.
(ix) State two precautions are taken to ensure accurate results
(b) )State two advantages of connecting identical cells in parallel.
(ii) State two factors to consider in choosing the material for the design of a resistor
A
depends on areas of the surfaces in contact
B
occurs in fluids
C
is independent of the relative velocity of the layers
D
depends on the tangential force between the layers
medium Difficulty
Verified Correct Answer: Option C
Physical Principles & Numerical Solution
R(n)
I(A)
V(v)
1.0
2.0
4.0
6.0
8.0
0.40
0.35
0.28
0.22
0.18
0.65
0.58
0.22
0.45
0.40
E = 3.00v
(x) Precautions:
- Key opened in between readings/key opened when readings were not taken
- Ensuring tight connections Avoid parallax error when taking a reading on voltmeter/ammeter Repeated readings (shown on the table)
- Noted/corrected zero error on voltmetre/ammeter
- Clean terminals ensured
(b)Advantages of connecting identical cells in parallel produce a larger amount of current. supply steady current for a long period - efficiency is high
(ii) Factors to consider in choosing a material for the design of a resistor
- Power rating-Tolerance
- Voltage rating
-Temperature coefficient
- Noise
- Frequency response
- Stability
- Resistivity
Source: Official Exam / Past Question Archive
Physics
UTME / JAMB 2019
Heat Energy & Temperature
Solution
A metal rod has a length of 100cm at 200°C. At what temperature will its length be 99.4cm. If the linear expansivity of the material of the rod is 2 × 10\(^{-5}\)C\(^{-1}\)
A
\(300^0C\)
B
\(200^0C\)
C
\(100^0C\)
D
\(-100^0C\)
medium Difficulty
Verified Correct Answer: Option D
Physical Principles & Numerical Solution
L\(_1\) = 100cm, T\(_1\) = 200^\circC
L\(_2\) = 99.4cm, T\(_2\) = ?
\alpha 2 \times 10\(^{-5}\) C\(^{-1}\)
\alpha
=
L\(_2\) - L\(_1\)
L\(_1\)(T\(_2\) - T\(_1\))
2
\times
10\(^{-5}\)
=
110 - 99.4
100(200 - T\(_2\))
=
0.6
100(200 - T\(_2\))
2 \times 10\(^{-5} \times 100(200 - T_2\)) = 0.6
200
-
T\(_2\)
=
0.6
0.002
=
300^\circC
T\(_2\) = 200 - 300 = -100^\circC
Source: WAEC / JAMB / NECO Classroom Archive (Record #55260)
Physics
WAEC / WASSCE 2019
Heat Energy & Temperature
Solution
Which of the following thermometers is used to measure the temperature of the human body?
A
Thermocouple
B
Alcohol-in-glass thermometer
C
Gas thermometer
D
Platinum resistance thermometer
medium Difficulty
Verified Correct Answer: Option B
Physical Principles & Numerical Solution
The range of usefulness of the thermometer is set by the boiling point of the liquid used. In the case of the ethanol-filled thermometer, the upper limit for measurement is 78 ^\circC (172.4 ^\circF), which makes it useful for measuring daytime, nighttime and body temperatures, although not for anything much hotter than these.
Source: WAEC / JAMB / NECO Classroom Archive (Record #59023)
Physics
WAEC / WASSCE 2019
Motion Force Circular Motion
Solution
An electron of mass 9.1 x 10\(^{-31}\) kg moves with a speed of 2.0 x 10\(^6\) ms\(^{-1}\) round the nucleus of an atom in a Circular path of radius 6.1 x 10(^{11}\) m. Determine the angular speed of the electron.
A
3.28 x 10\(^{16}\) rad s\(^{-1}\)
B
8.55 x 10\(^{3}\) rad s\(^{-1}\)
C
9.11 x 10\(^{13}\) rad s\(^{-1}\)
D
5.22 x 10\(^{15}\) rad s\(^{-1}\)
medium Difficulty
Verified Correct Answer: Option A
Physical Principles & Numerical Solution
Angular speed of the electron (W)
w = \(\frac{Velocity}{Radius} = \frac{V}{R}\)
= \(\frac{2.0 \times 10^6}{6.1 \times 10^{11}}\)
= 3.28 x 10\(^{16}\) rads\(^{-1}\)
Source: WAEC / JAMB / NECO Classroom Archive (Record #58963)
Physics
UTME / JAMB 2019
Equilibrium of Forces
Diagram
Solution
The diagram shows a uniform meter rule AB which balances horizontally at the 90cm mark when a mass of 0.2kg is suspended from B. Calculate the mass of the meter rule.
Attached Figure / Diagram
A
0.05kg
B
0.20kg
C
0.80kg
D
1.00kg
medium Difficulty
Verified Correct Answer: Option A
Physical Principles & Numerical Solution
M\(_r\)(90 - 50) = 0.2(100 - 90)
40M\(_r\) = 0.2 \times 10
M\(_r\) = \(\frac{2}{40}\) = 0.05kg
Source: WAEC / JAMB / NECO Classroom Archive (Record #55821)
Physics
WAEC / WASSCE 2019
Momentum Impulse Newtons Law of Motion
Solution
In an elastic collision, momentum is conserved as well as well as?
A
velocity
B
kinetic energy
C
potential energy
D
speed
medium Difficulty
Verified Correct Answer: Option B
Physical Principles & Numerical Solution
An elastic collision is an encounter (collision) between two bodies in which the total kinetic energy of the two bodies remains the same.
Source: WAEC / JAMB / NECO Classroom Archive (Record #58783)
Physics
UTME / JAMB 2019
Simple Harmonic Motion
Solution
A siren having a ring of 200 hole makes 132 rev/min. A jet of air is directed on the set of holes. Calculate the frequency and wavelength in air of the note produced (take v = 350m/s)
A
0.795m
B
0.625m
C
0.335m
D
0.125m
medium Difficulty
Verified Correct Answer: Option A
Physical Principles & Numerical Solution
n = 200, S = 132 rev/min, v = 350m/s\(^2\)
f
=
ns
=
200
\times
132
rev
min
\times
1min
60s
=
440Hz
\lambda
=
v
f
=
350
440
=
0.795m
Source: WAEC / JAMB / NECO Classroom Archive (Record #55265)
Physics
WAEC / WASSCE 2019
Density and Relative Density
Solution
An instrument used to measure relative humidity is the?
A
hygrometer
B
hydrometer
C
pyrometer
D
manometer
medium Difficulty
Verified Correct Answer: Option A
Physical Principles & Numerical Solution
A hydrometer is an instrument used for measuring the relative density of liquids based on the concept of buoyancy.
A hygrometer measures humidity, the amount of water vapor in air
Source: WAEC / JAMB / NECO Classroom Archive (Record #59028)
Physics
UTME / JAMB 2019
Electromagnetic Field
Diagram
Solution
A coil X is moved quickly away from the end Y of a stationary metal bar and a current then flows in X as shown above.
Then
Attached Figure / Diagram
A
the bar is not a magnet
B
Y is a north pole
C
Y is a South pole
D
Y repels coil X
medium Difficulty
Verified Correct Answer: Option B
Physical Principles & Numerical Solution
N - S magnet is moved towards a coil production clockwise direction of current in the coil.
- This is the same as a coil moved away from S-N (Y - North pole)
Source: WAEC / JAMB / NECO Classroom Archive (Record #55653)
Physics
WAEC / WASSCE 2019
Structure of the Nucleus
Solution
Which of the following statements about a neutral atom is correct? The
A
core is composed of electrons and protons
B
number of electrons is equal to that of neutron
C
number of neutrons is equal to that of protons
D
number of protons is equal to that of electrons.
medium Difficulty
Verified Correct Answer: Option D
Physical Principles & Numerical Solution
Atoms are neutral; they contain the same number of protons as electrons.
Source: WAEC / JAMB / NECO Classroom Archive (Record #59031)
Physics
WAEC / WASSCE 2019
Reflection of Light
Diagram
Solution
The diagram above represents an experimental set-up for verifying?
Attached Figure / Diagram
A
lens formula
B
refraction laws
C
reflection laws
D
mirror formula
medium Difficulty
Verified Correct Answer: Option A
Physical Principles & Numerical Solution
the diagram above is an experimental set up for verifying lens formula
Source: WAEC / JAMB / NECO Classroom Archive (Record #58810)
Physics
WAEC / WASSCE 2019
Refraction of Light
Solution
A ray of light traveling from a rectangular glass block of refractive index 1.5 into air strikes the block at an angle of incidence of 30. Calculate its angle of refraction.
A
48.6°
B
19.5°
C
20.0
D
45.0
medium Difficulty
Verified Correct Answer: Option A
Physical Principles & Numerical Solution
Given that refractive index = 1.5, angle of incidence = 30^\circ, angle of refraction =?
using snell's law = refractive index = \(\frac{sini}{sinr}\)
=\(\frac{1}{n } = \frac{sin30}{sinr}\)
= \(sinr = 1.5\times sin 30\)
r = \(sin^10.75\)
= 48.6^\circ
this is because ray is traveling from a more denser medium to a less dense medium
Source: WAEC / JAMB / NECO Classroom Archive (Record #59015)
Physics
WAEC / WASSCE 2019
Waves
Solution
Which of the following characteristics of waves can a ripple tank be used to demonstrate?
I. Reflection
II. Refraction
III. Diffraction
A
I, II and Ill
B
ll and ll only
C
l and lII only
D
I and II only
medium Difficulty
Verified Correct Answer: Option A
Physical Principles & Numerical Solution
ripple tank experiment can be used to demonstrate the following properties of waves:
Reflection
Refraction
Diffraction
Source: WAEC / JAMB / NECO Classroom Archive (Record #58888)