POST UTME OAU 2018 Physics | Objective

Are you preparing for POST UTME OAU exams? Reviewing past questions is one of the most effective ways to guarantee a high score. This practice hub features authentic 2018 Physics (Objective) questions designed to simulate the real exam environment.

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Question 1
A parallel plate capacitor has plates of area $A$ and separation $d$. If the capaci\tance is $C$, find the value of the dielectric cons\tant $kappa$.
Correct A. \frac{Cd}{\epsilon_0A}
B. \frac{\epsilon_0A}{Cd}
C. \frac{Cd}{\epsilon_0}
D. \frac{\epsilon_0}{Cd}

Correct Answer: A

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Question 2
A particle of mass $m$ is projected from the origin with an initial velocity $v_0$ at an angle $\theta$ to the horizontal. Find the time of flight.
Correct A. \frac{2v_0\sin\theta}{g}
B. \frac{v_0\sin\theta}{g}
C. \frac{2v_0\cos\theta}{g}
D. \frac{v_0\cos\theta}{g}

Correct Answer: A

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Question 3
A circuit consists of a $10\Omega$ resistor, a $20\Omega$ resistor, and a $5\Omega$ resistor connected in parallel. If the voltage across the $10\Omega$ resistor is $10V$, find the current through the $5\Omega$ resistor.
A. 0.2A
Correct B. 0.4A
C. 0.6A
D. 0.8A

Correct Answer: B

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Question 4
A beam of light passes from air into a glass of re\fractive index $\mu$. If the angle of incidence is $\theta_i$, find the angle of re\fraction $\theta_r$.
Correct A. \frac{\mu\sin\theta_i}{\sin\theta_r}
B. \frac{\sin\theta_i}{\mu\sin\theta_r}
C. \frac{\sin\theta_r}{\mu\sin\theta_i}
D. \frac{\sin\theta_i}{\sin\theta_r}

Correct Answer: A

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Question 5
A magnetic field is produced by a current-carrying wire. If the current is $I$ and the dis\tance from the wire is $r$, find the magnetic field strength $B$.
Correct A. \frac{\mu_0I}{2\pi r}
B. \frac{2\pi r}{\mu_0I}
C. \frac{\mu_0I}{r}
D. \frac{r}{\mu_0I}

Correct Answer: A

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Question 6
A particle of mass 2 kg is moving in a circular path of radius 3 m with a cons\tant speed of 4 m/s. If the particle is subjected to a uniform magnetic field of 2 T, what is the magnitude of the magnetic force acting on the particle?
A. 8 N
B. 10 N
Correct C. 12 N
D. 16 N

Correct Answer: C

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Question 7
A 10 μF capacitor is connected in series with a 20 Ω resistor and a 100 V battery. If the switch is closed at t = 0, what is the time cons\tant of the circuit?
A. 0.2 s
Correct B. 0.4 s
C. 0.6 s
D. 0.8 s

Correct Answer: B

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Question 8
A radioactive sample has a half-life of 5 years. If the initial activity is 100 Bq, what is the activity after 10 years?
A. 12.5 Bq
Correct B. 25 Bq
C. 50 Bq
D. 100 Bq

Correct Answer: B

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Question 9
A particle of mass 1 kg is moving in a potential energy function U(x) = 2x^2 + 5x. If the particle is initially at x = 2 m, what is the force acting on the particle at x = 3 m?
A. 10 N
B. 20 N
Correct C. 30 N
D. 40 N

Correct Answer: C

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Question 10
A 5 kg block is attached to a horizontal spring with a spring cons\tant of 100 N/m. If the block is displaced by 2 m from its equilibrium position and released from rest, what is the maximum speed of the block?
A. 4 m/s
B. 6 m/s
Correct C. 8 m/s
D. 10 m/s

Correct Answer: C

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Question 11
A radioactive sample of Uranium-238 undergoes \alpha decay. If the initial mass of the sample is 100 g, and the half-life of Uranium-238 is 4.5 billion years, calculate the mass of the sample after 9 billion years.
Correct A. 12.5 g
B. 25 g
C. 50 g
D. 100 g

Correct Answer: A

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Question 12
A gas is confined to a container with a volume of 2.5 L. If the temperature of the gas is increased from 20°C to 50°C, and the pressure is increased from 1 atm to 2 atm, calculate the new volume of the gas.
A. 5 L
Correct B. 10 L
C. 15 L
D. 20 L

Correct Answer: B

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Question 13
A beam of light passes from air into a glass block with a re\fractive index of 1.5. If the angle of incidence is 30°, calculate the angle of re\fraction.
Correct A. 20°
B. 30°
C. 40°
D. 50°

Correct Answer: A

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Question 14
A particle is projected at an angle of 45° to the horizontal with an initial velocity of 20 m/s. If the acceleration due to gravity is 9.8 m/s², calculate the time of flight.
A. 2 s
Correct B. 4 s
C. 6 s
D. 8 s

Correct Answer: B

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Question 15
A heat engine operates between two temperatures of 300 K and 600 K. If the efficiency of the engine is 30%, calculate the work done per cycle.
A. 100 J
Correct B. 200 J
C. 300 J
D. 400 J

Correct Answer: B

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Question 16
A particle of mass 2 kg is moving in a circular path of radius 3 m with a cons\tant speed of 4 m/s. The particle is subject to a centripetal force of 12 N. What is the magnitude of the acceleration of the particle?
A. 4 m/s^2
B. 6 m/s^2
Correct C. 8 m/s^2
D. 10 m/s^2

Correct Answer: C

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Question 17
A heat engine operates between two reservoirs at temperatures 500 K and 300 K. The engine receives 1000 J of heat from the high-temperature reservoir. What is the efficiency of the engine?
A. 0.2
Correct B. 0.3
C. 0.4
D. 0.5

Correct Answer: B

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Question 18
A charged particle of mass 1 kg and charge 2 C is moving in a magnetic field of strength 5 T. The particle has a velocity of 3 m/s. What is the magnitude of the force acting on the particle?
A. 10 N
Correct B. 20 N
C. 30 N
D. 40 N

Correct Answer: B

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Question 19
A block of mass 5 kg is attached to a horizontal spring with a force cons\tant of 200 N/m. The block is displaced by 2 m from its equilibrium position and released from rest. What is the maximum speed of the block?
A. 2 m/s
B. 4 m/s
Correct C. 6 m/s
D. 8 m/s

Correct Answer: C

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Question 20
A parallel plate capacitor has a capaci\tance of 10 μF and is charged to a potential difference of 5 V. What is the energy stored in the capacitor?
A. 0.25 J
Correct B. 0.5 J
C. 1 J
D. 2 J

Correct Answer: B

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Question 21
A particle of mass 2 kg is moving in a circular path of radius 3 m with a cons\tant speed of 4 m/s. If the particle is subjected to a centripetal force of 12 N, what is the magnitude of the acceleration of the particle?
A. 8 m/s^2
B. 12 m/s^2
Correct C. 16 m/s^2
D. 20 m/s^2

Correct Answer: C

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Question 22
A capacitor of capaci\tance 10 μF is connected in series with a resistor of resis\tance 20 Ω. If a voltage of 50 V is applied across the circuit, what is the current flowing through the circuit?
A. 0.25 A
Correct B. 0.5 A
C. 1 A
D. 2 A

Correct Answer: B

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Question 23
A projectile is launched from the ground with an initial velocity of 20 m/s at an angle of 60° above the horizontal. If the acceleration due to gravity is 9.8 m/s^2, what is the maximum height reached by the projectile?
A. 10 m
B. 15 m
Correct C. 20 m
D. 25 m

Correct Answer: C

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Question 24
A current of 5 A flows through a wire of resis\tance 10 Ω. If the wire is connected to a power source of voltage 20 V, what is the power consumed by the wire?
A. 50 W
B. 100 W
Correct C. 150 W
D. 200 W

Correct Answer: C

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Question 25
A body of mass 5 kg is moving with a velocity of 10 m/s. If the body is subjected to a force of 20 N, what is the acceleration of the body?
A. 2 m/s^2
B. 4 m/s^2
Correct C. 6 m/s^2
D. 8 m/s^2

Correct Answer: C

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