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Physics
WAEC / WASSCE 2020
Heat Energy & Temperature
The depolarising agent in a Leclanche cell is?
A
carbon rod
B
ammonium chloride
C
manganese (IV) oxide
D
zinc plate
medium Difficulty
Verified Correct Answer: Option C
Physical Principles & Numerical Solution
No expanded working has been attached for this question yet. The verified answer is Option C.
Source: Myschool Past Questions Archive (Record #59370)
Physics
WAEC / WASSCE 2020
Heat Energy & Temperature
The material used to slow down the neutrons in a nuclear reactor is
A
boron
B
copper
C
graphite
D
uranium
medium Difficulty
Verified Correct Answer: Option C
Physical Principles & Numerical Solution
No expanded working has been attached for this question yet. The verified answer is Option C.
Source: Myschool Past Questions Archive (Record #59371)
Physics
WAEC / WASSCE 2020
Heat Energy & Temperature
Which of the following statements explain why hot soapy water is more effective in cleaning oil-stained dishes?
A
The oil on the dishes repels the soap
B
soap and heat decrease the surface tension of oil
C
soap increases the surface tension of oil and water
D
Hot water increases the surface tension of oil
medium Difficulty
Verified Correct Answer: Option B
Physical Principles & Numerical Solution
No expanded working has been attached for this question yet. The verified answer is Option B.
Source: Myschool Past Questions Archive (Record #59372)
Physics
WAEC / WASSCE 2020
Heat Energy & Temperature
A 60kg man stands on a weighing balance in an elevator. If the elevator accelerates upwards at 5ms\(^{-2}\), determine the reading of the scale. [g = 10ms\(^{-2}\)]
A
300N
B
600N
C
800N
D
900N
medium Difficulty
Verified Correct Answer: Option D
Physical Principles & Numerical Solution
No expanded working has been attached for this question yet. The verified answer is Option D.
Source: Myschool Past Questions Archive (Record #59414)
Physics
WAEC / WASSCE 2020
Electricity and Magnetism
A moving-coil galvanometer which gives a full-scale on deflection with 0.005A is converted to a voltmeter reading up to 5V using an external resistance of 975\(\Omega\). What is the resistance of the metre?
A
0.25\(\Omega\)
B
2.50\(\Omega\)
C
25.00\(\Omega\)
D
250.00\(\Omega\)
medium Difficulty
Verified Correct Answer: Option C
Physical Principles & Numerical Solution
No expanded working has been attached for this question yet. The verified answer is Option C.
Source: Myschool Past Questions Archive (Record #59422)
Physics
WAEC / WASSCE 2020
Electricity and Magnetism
A beam consisting of \(\alpha\)-particles. \(\beta\)-particles and \(\gamma\)-rays pass through a magnetic field at right angles to the direction of the field. Which of the following observations would be made about the \(\alpha\)-particles, \(\beta\)-particles, and \(\gamma\)-rays respectively?
A
Deflected, deflected, deflected
B
Deflected, deflected, not deflected
C
Deflected, not deflected, deflected
D
Not deflected, deflected, deflected
medium Difficulty
Verified Correct Answer: Option B
Physical Principles & Numerical Solution
No expanded working has been attached for this question yet. The verified answer is Option B.
Source: Myschool Past Questions Archive (Record #59427)
Physics
WAEC / WASSCE 2020
Electricity and Magnetism
Solution
A parallel plate capacitor is charged and the charging battery is subsequently disconnected. lf the plates of the capacitor are moved farther apart by means of insulating handles, the
A
capacitance would increase
B
capacitance would decrease
C
charge on the capacitor would increase
D
charge on the capacitor would decrease
medium Difficulty
Verified Correct Answer: Option B
Physical Principles & Numerical Solution
As the distance between the plates increases, the ability of the capacitor to store charge (capacitance) decreases. Since the battery is disconnected, the charge remains constant, but the voltage across the plates increases.
Source: Myschool Past Questions Archive (Record #59435)
Physics
WAEC / WASSCE 2020
Mechanics and Properties of Matter
The earpiece of a telephone handset converts energy from
A
electrical to sound
B
sound to electrical
C
sound to electrical
D
sound to radio wave
medium Difficulty
Verified Correct Answer: Option A
Physical Principles & Numerical Solution
No expanded working has been attached for this question yet. The verified answer is Option A.
Source: Myschool Past Questions Archive (Record #59394)
Physics
WAEC / WASSCE 2020
Mechanics and Properties of Matter
Solution
The magnitude of the force experienced by a charge of 1.6 x 10\(^{-8}\)C in a uniform electric field of intensity 5 x 10\(^5\)NC\(^{-1}\) is
A
3.2 x 10\(^{-14}\)N
B
8.0 x 10\(^{-13}\)N
C
8.0 x 10\(^{-3}\)N
D
3.1 x 10\(^{13}\) N
medium Difficulty
Verified Correct Answer: Option C
Physical Principles & Numerical Solution
E = \(\frac{\text{F}}{\text{q}}\)
Force F = E x q
F = 5 x 10\(^5\) x 1.6 x 10\(^{-8}\) = 8.0 x 10\(^{-3}\)N
Source: Myschool Past Questions Archive (Record #59458)
Physics
WAEC / WASSCE 2020
Mechanics and Properties of Matter
Solution
A motorcycle starting from rest is uniformly accelerated such that its velocity in 10s is 72kmhr\(^{-1}\). What is its acceleration?
A
108ms\(^2\)
B
86ms\(^2\)
C
4ms\(^2\)
D
2ms\(^2\)
medium Difficulty
Verified Correct Answer: Option D
Physical Principles & Numerical Solution
where u = o m/s, t = 10s,
v = 72kmhr\(^{-1}\) ---> (72 X 1000) / 3600
: v = 20 m/s
Acceleration (a) = ( v - u ) / t ---> (20 - 0) / 10
: a = 2m/s\(^2\)
Source: Myschool Past Questions Archive (Record #59460)
Physics
WAEC / WASSCE 2020
Thermal Physics
Solution
The temperature of an object is raised by 120^\circC. The resulting increase in its absolute temperature is
A
50K
B
120 K
C
200K
D
393K
medium Difficulty
Verified Correct Answer: Option B
Physical Principles & Numerical Solution
Object temperature = 120ºC
So, 0ºC + 273 = K
K = 120 + 273 = 393K
Increase in temperature = 0ºC to 120ºC
⇒ 273K to 393K = ( 393 - 273) = 120K
NOTE: The change in temperature in Kelvin is equal to the change in temperature in Celsius: \DeltaT(K) = \DeltaT(^\circC)
Source: Myschool Past Questions Archive (Record #59461)
Physics
WAEC / WASSCE 2020
Heat Energy & Temperature
Which of the following statements about the motion of a simple pendulum is true?
A
It is a simple harmonic motion when the angle of displacement is large
B
It passes the equilibrium position with minimum speed
C
It possesses maximum kinetic energy at the extreme positions
D
lt swings faster at the poles than at the equator
medium Difficulty
Verified Correct Answer: Option D
Physical Principles & Numerical Solution
No expanded working has been attached for this question yet. The verified answer is Option D.
Source: Myschool Past Questions Archive (Record #59462)
Physics
WAEC / WASSCE 2020
Mechanics and Properties of Matter
Solution
The velocity of sound in air at 15^\circC is 340ms\(^{-1}\). Calculate the velocity at 47\(^o\)C
A
790ms\(^{-1}\)
B
602ms\(^{-1}\)
C
358ms\(^{-1}\)
D
322ms\(^{-1}\)
medium Difficulty
Verified Correct Answer: Option C
Physical Principles & Numerical Solution
Given the velocity of sound at \( 15^\circ C \):
\(v_0 = 340 \, \text{m/s}\)
The absolute temperatures are:
\(T_0 = 15 + 273.15 = 288.15 \, \text{K}\)
\(T = 47 + 273.15 = 320.15 \, \text{K}\)
We use the formula for the velocity of sound:
\(v = v_0 \sqrt{\frac{T}{T_0}}\)
Substituting the known values:
\(v = 340 \times \sqrt{\frac{320.15}{288.15}}\)
Calculating the ratio of temperatures:
\(\frac{320.15}{288.15} \approx 1.111\)
Taking the square root:
\(\sqrt{1.111} \approx 1.054\)
Finally, calculating the new velocity:
\(v \approx 340 \, \text{m/s} \times 1.054 \approx 358.6 \, \text{m/s}\)
The velocity of sound in air at \( 47^\circ C \) is approximately:
\(v \approx 358.6 \, \text{m/s}\)
Source: Myschool Past Questions Archive (Record #59437)
Physics
WAEC / WASSCE 2020
Mechanics and Properties of Matter
A 500N box rests on a horizontal floor. A constant horizontal force is exerted on the box so that it moves through 8m. If the coefficient of kinetic friction between the floor and the box is 0.22, calculate the workdone on the box
A
880J
B
440J
C
400J
D
110J
medium Difficulty
Verified Correct Answer: Option A
Physical Principles & Numerical Solution
No expanded working has been attached for this question yet. The verified answer is Option A.
Source: Myschool Past Questions Archive (Record #59446)
Physics
WAEC / WASSCE 2020
Mechanics and Properties of Matter
Diagram
Solution
The diagram illustrates a ball of mass m sliding down a plank inclined at an angle of 0 to the horizontal. The kinetic friction between the ball and the plank is F, and the acceleration of free fall is g. The normal force on the ball is?
Attached Figure / Diagram
A
mgsin \(\theta\)
B
mgtan \(\theta\), mgcos \(\theta\)
C
mgcos \(\theta\)
D
mgcot \(\theta\)
medium Difficulty
Verified Correct Answer: Option C
Physical Principles & Numerical Solution
The normal reaction/force on a body on a horizontal surface is R = mg; but that on a body on an inclined surface is R = mgCos\theta.
Source: Myschool Past Questions Archive (Record #59449)