Form 4 Physics national exam 2021 with answers
The 2021 Form 4 national exam paper for Form 4 Physics, question by question. Take it timed like the real exam, then see the answer and explanation to every question.
- 48 questions, 100 marks
- 120 minutes
Take this paper
120 minutes, 100 marks. Multiple choice is marked for you; you mark your written answers against the marking points.
A free account is needed to start, so your answers and results are saved.
Instructions to candidates
Answer all questions in the ANSWER BOOKLET. Time: 2 hours.
Part one: Circle the correct letter for the following answers (40 marks)
- 12 marks
Which of the following waves is an example of electromagnetic wave:
- A.Sound wave
- B.String wave
- C.water waves
- D.Radio waves
- 22 marks
When the vibrations of the particles are perpendicular to the direction of wave motion is
- A.Surface wave
- B.Longitudinal waves
- C.Transverse wave
- D.Seismic wave
- 32 marks
The speed of sound in air at a temperature of -40°C is
- A.370 m/s
- B.290 m/s
- C.350 m/s
- D.306 m/s
- 42 marks
The forward and backward motion of an object from its mean position is
- A.Periodic Motion
- B.Circular motion
- C.Oscillatory motion
- D.Linear motion
- 52 marks
A school bus emits sound of wavelength 0.5m and frequency 100 Hz, then its velocity is:
- A.20 m/s
- B.50 m/s
- C.200 m/s
- D.0.5 m/s
- 62 marks
The wavelength of fundamental harmonic of 1.5m long open pipe is:
- A.1m
- B.0.5m
- C.3m
- D.2.0m
- 72 marks
If the object is placed at a distance of 20cm in front of a plane mirror, the distance between the object and the image is
- A.60cm
- B.20cm
- C.30cm
- D.40cm
- 82 marks
If a pendulum clock is taken on a mountaintop, its period will be
- A.Increased
- B.Decreased
- C.Unchanged
- D.Squared
- 92 marks
The measure of rigidity (stiffness) of a spring is
- A.Force constant
- B.Elastic limit
- C.Stress
- D.Strain
- 102 marks
A tree is placed 15cm from a converging mirror of radius curvature 20cm. The distance of the image is
- A.60cm
- B.6cm
- C.15cm
- D.30cm
- 112 marks
To detect an original diamond from fake diamond, we use
- A.Infra red light
- B.Ultraviolet light
- C.Green light
- D.Emitting light
- 122 marks
In order to find the direction of inducing current we use
- A.Faraday's law
- B.Charles' law
- C.Lenz's law
- D.Ampere's law
- 132 marks
The maximum voltage in an AC circuit is 35V and its angle is 45°. The instantaneous voltage is:
- A.50V
- B.24.7V
- C.17.5V
- D.25.8V
- 142 marks
Blue light has a frequency of 7.7x10^14 Hz. The energy of this photon is: (use h = 6.6x10^-34 Js)
- A.50.8x10^-21 J
- B.8.6x10^-49 J
- C.1.17x10^48 J
- D.5.1x10^-19 J
- 152 marks
If the decay constant of a radioactive sample is 1.72x10^-4 decay/sec, its half-life is:
- A.9024 sec
- B.2.482 sec
- C.2904 sec
- D.4029 sec
- 162 marks
An element of 141/54 B (mass number 141, atomic number 54). The number of neutrons is:
- A.54
- B.141
- C.87
- D.195
- 172 marks
In forward biasing, the potential barrier is:
- A.Increased
- B.Decreased
- C.Unchanged
- D.Variable
- 182 marks
A 4H inductor is connected to a 120V and 60Hz source; the inductive reactance is
- A.754 Ω
- B.767 Ω
- C.574 Ω
- D.1508 Ω
- 192 marks
A 60cm long wire flows at 4m/s vertically over a strength of magnetic field at 3T. The EMF induced in it is:
- A.0.72V
- B.7.2V
- C.720V
- D.72V
- 202 marks
A night vision device can see it in darkness by receiving a kind of radiation known as:
- A.Ultraviolet rays
- B.infrared radiation
- C.Cosmic rays
- D.Gamma rays
Part two: Structured Questions (60 marks)
Question One: Oscillatory motion (13); Question Two: Refraction of light (18); Question Three: Wave motion (9); Question Four: Sound waves (10); Question Five: Dispersion of light (10).
- Q1.1a2 marks
Zahra oscillates a swing and makes 100 complete cycles in 20 seconds. Find: a. Period (2 marks)
- Q1.1b2 marks
Zahra oscillates a swing and makes 100 complete cycles in 20 seconds. Find: b. Frequency (2 marks)
- Q1.1c2 marks
Zahra oscillates a swing and makes 100 complete cycles in 20 seconds. Find: c. Angular frequency (2 marks)
- Q1.23 marks
Define amplitude (3 marks)
- Q1.34 marks
Ali stretched a spring at a distance of 20cm and held. What is the potential energy stored in the spring? (take K = 200N/m) (4 marks)
- Q2.14 marks
Define refraction of light (4 marks)
- Q2.22 marks
When a ray of light strikes the surface of separation of two different media perpendicularly, then it does not suffer any _____ (reflection, refraction) (2 marks)
- Q2.3a2 marks
Below is a convex lens (the object stands at 2F1, see the diagram). a) Complete the ray diagram to locate the position of image (2 marks)
- Q2.3b2 marks
Below is a convex lens (the object stands at 2F1, see the diagram). b) What will be the characteristics of that image (2 marks)
- Q2.3c2 marks
Below is a convex lens (the object stands at 2F1, see the diagram). c) What will be the use of this case (2 marks)
- Q2.4a2 marks
Somali optic company produces two lenses, A and B, which have focal length of 50cm and -20cm respectively. a) What is the nature of lens A and Lens B? (2 marks)
- Q2.4b2 marks
Somali optic company produces two lenses, A and B, which have focal length of 50cm and -20cm respectively. b) What is the power of lens A and Lens B? (2 marks)
- Q2.4c2 marks
Somali optic company produces two lenses, A and B, which have focal length of 50cm and -20cm respectively. c) What is the power of combination if lenses A and B are held close together? (2 marks)
- Q3.14 marks
State the types of waves (4 marks)
- Q3.23 marks
Radio Mogadishu produces waves of frequency of 90MHZ and wavelength 3.33m. calculate the speed of the waves (3 marks)
- Q3.32 marks
The frequency of a wave triples and its wavelength doubles. What happens to its speed? (2 marks)
- Q4.12 marks
Differentiate between infrasonic and ultrasonic sounds (2 marks)
- Q4.22 marks
Describe sound as a longitudinal wave (2 marks)
- Q4.31 mark
State properties of sound waves
- Q4.43 marks
Sound travels slowest in _____ faster in _____ and fastest in _____ (3 marks)
- Q4.5a1.5 marks
Amin Ambulance moves with the speed of 35m/s, its siren emitting sound at a frequency of 600Hz. What sound is heard by Hassan standing at the Bakara Station as the ambulance a) approaches (Take v = 345m/s)
- Q4.5b1.5 marks
Amin Ambulance moves with the speed of 35m/s, its siren emitting sound at a frequency of 600Hz. What sound is heard by Hassan standing at the Bakara Station as the ambulance b) recedes (Take v = 345m/s)
- Q5.12 marks
Differentiate between primary and secondary colors (2 marks)
- Q5.23 marks
Halima has a green filter and shines a yellow light, what color will it transmit? (3 marks)
- Q5.3a1 mark
Use the following words to complete the gaps (Red, Violet, Ultraviolet, Infrared rays, Gamma rays): a. Which colour of white light has the least deviation _____ (1 mark)
- Q5.3b2 marks
Use the following words to complete the gaps (Red, Violet, Ultraviolet, Infrared rays, Gamma rays): b. It is used to detect forgery of cheques or important documents _____ (2 marks)
- Q5.3c1 mark
Use the following words to complete the gaps (Red, Violet, Ultraviolet, Infrared rays, Gamma rays): c. It produces a heating effect _____ (1 mark)
- Q5.3d1 mark
Use the following words to complete the gaps (Red, Violet, Ultraviolet, Infrared rays, Gamma rays): d. A colour which has a maximum refraction _____ (1 mark)
Paper set by the Federal Ministry of Education, Culture and Higher Education (MoECHE), Somalia. Shared free of charge to help students prepare. The answers and explanations are written by Sheerxirfad teachers.
