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Physics
WAEC / WASSCE 2021
Waves, Sound & Vibrations
Diagram
Solution
The sketched graph above represents a progressive wave moving from the left to the right. The period of the wave is 0.125s.
Determine the values of the amplitude and wavelength, respectively, of the wave.
Attached Figure / Diagram
A
8 cm; 27 cm
B
8 cm; 9 cm
C
4 cm; 9 cm
D
16 cm; 27 cm
medium Difficulty
Verified Correct Answer: Option B
Physical Principles & Numerical Solution
Amplitude = 16cm/2 = 8cm ( displacement from mean position)
3\(\lambda\) = 27cm
\(\lambda\) = \(\frac{27}{3}\) = 9cm
Therefore, amplitude(A) = 8cm and \(\lambda\) = 9cm
Source: Myschool Past Questions Archive (Record #61934)
Physics
WAEC / WASSCE 2021
Current Electricity & Electric Circuits
Solution
A wire of cross-sectional area 2\pi x 10\(^-{8}\) m\(^2\) and resistivity 1.1 x 10\(^-{8}\) \Omega m, has a resistance of 21\Omega.
Calculate the length of the wire. [\pi=22/7]
A
180 m
B
140 m
C
120 m
D
240 m
medium Difficulty
Verified Correct Answer: Option C
Physical Principles & Numerical Solution
To calculate the length of the wire, we use the formula for resistance:
\(R = \frac{\rho \cdot L}{A}\)
Where:
- \( R \) is the resistance (21 \Omega),
- \( \rho \) is the resistivity (\( 1.1 \times 10^{-8} \, \Omega \, m \)),
- \( L \) is the length of the wire,
- \( A \) is the cross-sectional area (\( 2\pi \times 10^{-8} \, m^2 \)).
Rearranging the formula to solve for length \( L \): \(L = \frac{R \cdot A}{\rho}\)
Substituting the known values, we first calculate the area \( A \):
\(A = 2\pi \times 10^{-8} \, m^2 = 2 \times \frac{22}{7} \times 10^{-8} \approx 8.0 \times 10^{-8} \, m^2\)
Now substitute into the length formula: \(L = \frac{21 \, \Omega \cdot 8.0 \times 10^{-8} \, m^2}{1.1 \times 10^{-8} \, \Omega \, m}\)
Calculating:
\(L = \frac{21 \cdot 8.0}{1.1}\)m
\(L = \frac{168}{1.1} \, m \approx 120\)m
Source: Myschool Past Questions Archive (Record #62299)
Physics
WAEC / WASSCE 2021
Current Electricity & Electric Circuits
Solution
Which of the following statements best describes the particles in a solid at room temperature? They are
A
far apart and moving randomly.
B
close together and vibrating.
C
close together and stationary.
D
close together and moving randomly.
medium Difficulty
Verified Correct Answer: Option B
Physical Principles & Numerical Solution
The particles of a solid are packed closely together. The forces between the particles are strong enough that the particles cannot move freely; they can only vibrate. As a result, a solid has a stable, definite shape and a definite volume.
Source: Myschool Past Questions Archive (Record #62300)
Physics
WAEC / WASSCE 2021
Current Electricity & Electric Circuits
A rotating disc contains a set of holes in a circle. An air jet is directed onto the holes and a note of frequency 480 Hz is produced. If the number of holes is 20, calculate the speed of rotation of the disc.
A
10 rev/s
B
20 rev/s
C
24 rev/s
D
8 rev/s.
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 #62302)
Physics
WAEC / WASSCE 2021
Work, Energy, Power & Simple Machines
Solution
A force of 10 N, acting continuously, increases the kinetic energy of an object from 20.J to 60 J. Find the distance moved by the object.
A
200m
B
40m
C
4m
D
400m
medium Difficulty
Verified Correct Answer: Option C
Physical Principles & Numerical Solution
according to the work-energy theorem; Workdone = change in kinetic energy.
W = ∆ K.E
force x distance = \(K.E_2 - K.E_2\)
10 x s = 60 - 20
s = \(\frac{40}{10}\) = 4m.
Source: Myschool Past Questions Archive (Record #62303)
Physics
WAEC / WASSCE 2021
Current Electricity & Electric Circuits
An electric circuit consists of a resistor. a battery and a key. If the voltage of the battery is increased, there Would be an increase in the?
A
current and resistance only.
B
current resistance and temperature.
C
current and temperature only.
D
resistance and temperature only
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 #62304)
Physics
WAEC / WASSCE 2021
Atomic, Quantum, Nuclear Physics & Electronics
A radioactive material has a half-life of 1.0 hour If 200.0 g of it was present at 6 a.m. on a certain day, how many grams will have decayed by 9 a.m. on the same day?
A
175.0 g
B
150.0 g
C
100.0 g
D
187.5 g
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 #62305)
Physics
WAEC / WASSCE 2021
Current Electricity & Electric Circuits
Solution
The following statements about a loudspeaker are correct except?
A
its contains a permanent magnet.
B
sound signal converted to varying current signal enters the speech coil.
C
the current in the speech coil creates a magnetic force on the coil.
D
the magnetic force on the speech coil is uni-directional.
medium Difficulty
Verified Correct Answer: Option D
Physical Principles & Numerical Solution
The magnetic force on the voice coil is bi-directional, allowing it to move back and forth, producing sound waves.
Source: Myschool Past Questions Archive (Record #62306)
Physics
WAEC / WASSCE 2021
Calorimetry, Latent Heat & Change of State
An ice cube has mass of 20 g at 5^\circC. Calculate the energy required to raise its temperature to 0^\circC. [Specific heat capacity of ice = 2.1 J/g^\circc]
A
105 J
B
100 J
C
42 J
D
210 J
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 #62307)
Physics
WAEC / WASSCE 2021
Linear Motion, Projectiles & Kinematics
Solution
A stone is thrown horizontally with initial velocity 15m/s from a tower 20 m high. How long does it take to reach the ground? [g= 10m/s\(^2\)
A
2s
B
4s
C
5s
D
1s
medium Difficulty
Verified Correct Answer: Option A
Physical Principles & Numerical Solution
\(h = \frac{1}{2} g t^2\), at max height v = 0m/s
Given: h = 20m, g = 10 ms\(^2\)
Rearranging:
\(t^2 = \frac{2h}{g} = \frac{2 \times 20}{10} = 4\)
\(t = \sqrt{4}\) = 2s
Thus, the time to reach the ground is: t = 2s
Source: Myschool Past Questions Archive (Record #62308)
Physics
WAEC / WASSCE 2021
Magnetism, Electromagnetism & AC Circuits
The electrons in a cathode-ray tube are produced by?
A
heating a metal filament.
B
ionization of the air.
C
applying a magnetic field to the y-plates.
D
applying an electric field to the x-plates.
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 #62310)
Physics
WAEC / WASSCE 2021
Scalars, Vectors & Relative Motion
Which of the following statements about distance and displacement is not correct?
A
Displacement is a vector quantity.
B
Distance has dimension
C
Displacement is measured in meters.
D
Distance is a vector quantity.
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 #62311)
Physics
WAEC / WASSCE 2021
Waves, Sound & Vibrations
A note produced by an instrument is distinguished from a similar note produced by another instrument by the?
A
intensity,
B
pitch.
C
overtones.
D
loudness
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 #62312)
Physics
WAEC / WASSCE 2021
Elasticity, Density, Pressure & Fluids
According to Pascal's principle, the pressure in a fluid is always?
A
dependent on density of the fluid.
B
distributed partially in all directions.
C
transmitted equally in all directions.
D
increasing with height.
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 #62313)
Physics
WAEC / WASSCE 2021
Current Electricity & Electric Circuits
Which of the following set of quantities have members which are all vectors?
A
Pressure, energy and force
B
Force, displacement and momentum
C
Distance, acceleration and work
D
Density, volume and weight
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 #62314)