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POST UTME UNN 2020 Physics | Objective

Are you preparing for POST UTME UNN exams? Reviewing past questions is one of the most effective ways to guarantee a high score. This practice hub features authentic 2020 Physics (Objective) questions designed to simulate the real exam environment.

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Question 1

A 2.5 mH inductor is connected in series with a 10 V AC source. If the frequency of the source is 50 Hz, what is the inductive reac\tance of the circuit?

Correct A. \( 2.5 \times 10^{-3} \times 2 pi \times 50 \) Ω

B. \( 2.5 \times 10^{-3} \times 2 pi \times 100 \) Ω

C. \( 2.5 \times 10^{-3} \times 2 pi \times 150 \) Ω

D. \( 2.5 \times 10^{-3} \times 2 pi \times 200 \) Ω

Correct Answer: A

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Question 2

A body of mass 5 kg is moving in a circular path with a radius of 2 m. If the body is subjected to a centripetal acceleration of 10 m/s^2, what is the force acting on the body?

Correct A. \( 5 \times 10 \) N

B. \( 5 \times 20 \) N

C. \( 5 \times 30 \) N

D. \( 5 \times 40 \) N

Correct Answer: A

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Question 3

A 100 W bulb is connected to a 230 V AC source. If the power factor of the circuit is 0.8, what is the current drawn by the bulb?

Correct A. \( \frac{100}{230 \times 0.8} \) A

B. \( \frac{100}{230 \times 0.9} \) A

C. \( \frac{100}{230 \times 0.7} \) A

D. \( \frac{100}{230 \times 0.6} \) A

Correct Answer: A

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Question 4

A 5 kg body 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?

Correct A. \( \frac{20}{5} \) m/s^2

B. \( \frac{20}{10} \) m/s^2

C. \( \frac{20}{15} \) m/s^2

D. \( \frac{20}{20} \) m/s^2

Correct Answer: A

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Question 5

A 2.5 mH inductor is connected in series with a 10 V AC source. If the frequency of the source is 50 Hz, what is the inductive reac\tance of the circuit?

Correct A. \( 2.5 \times 10^{-3} \times 2 pi \times 50 \) Ω

B. \( 2.5 \times 10^{-3} \times 2 pi \times 100 \) Ω

C. \( 2.5 \times 10^{-3} \times 2 pi \times 150 \) Ω

D. \( 2.5 \times 10^{-3} \times 2 pi \times 200 \) Ω

Correct Answer: A

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Question 6

A light ray passes from air into a glass slab of thickness 6 cm and re\fractive index 1.5. If the angle of incidence is 30°, calculate the angle of re\fraction.

A. 20°

Correct B. 25°

C. 30°

D. 35°

Correct Answer: B

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Question 7

A particle moves in a straight line with an initial velocity of 5 m/s and an acceleration of 2 m/s². If the particle's velocity is 10 m/s at time t = 2 s, calculate the time taken for the particle to reach a velocity of 15 m/s.

A. 3 s

Correct B. 5 s

C. 7 s

D. 9 s

Correct Answer: B

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Question 8

A wave has a frequency of 50 Hz and a wavelength of 0.2 m. If the wave is traveling in a medium with a speed of 100 m/s, calculate the amplitude of the wave.

A. 1 m

Correct B. 2 m

C. 3 m

D. 4 m

Correct Answer: B

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Question 9

A block of mass 5 kg is attached to a spring with a spring cons\tant of 100 N/m. If the block is displaced by 0.2 m from its equilibrium position and released, calculate the time period of the resulting simple harmonic motion.

A. 0.5 s

Correct B. 0.628 s

C. 1 s

D. 1.5 s

Correct Answer: B

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Question 10

A light ray passes through a prism with an angle of incidence of 30° and an angle of re\fraction of 20°. If the prism has a re\fractive index of 1.5, calculate the angle of emergence.

A. 25°

B. 30°

Correct C. 35°

D. 40°

Correct Answer: C

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Question 11

A radioactive sample emits \alpha particles with a half-life of 5 days. If the initial activity is 100 Bq, what is the activity after 10 days?

Correct A. 12.5 Bq

B. 25 Bq

C. 50 Bq

D. 100 Bq

Correct Answer: A

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Question 12

A 10 V battery is connected to a 2 Ω resistor in series with a 4 Ω resistor. What is the current in the circuit?

Correct A. 1.25 A

B. 2.5 A

C. 5 A

D. 10 A

Correct Answer: A

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Question 13

A gas is heated from 20°C to 50°C. If the initial volume is 2 L, what is the final volume?

A. 4 L

B. 6 L

Correct C. 8 L

D. 10 L

Correct Answer: C

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Question 14

A capacitor is charged to 10 μC. If the capaci\tance is 2 μF, what is the potential difference across the capacitor?

A. 5 V

Correct B. 10 V

C. 20 V

D. 50 V

Correct Answer: B

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Question 15

A 10 Ω resistor is connected to a 20 Ω resistor in parallel. What is the equivalent resis\tance?

A. 5 Ω

B. 10 Ω

Correct C. 15 Ω

D. 20 Ω

Correct Answer: C

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Question 16

A radioactive sample of Δₗ emits Δₗ particles at a rate of 1.5 ± 0.1 decays per minute. If the half-life of Δₗ is 5.27 ± 0.02 minutes, what is the mean lifetime of the sample?

Correct A. ( 3.45 pm 0.23 ) minutes

B. ( 6.54 pm 0.41 ) minutes

C. ( 9.63 pm 0.59 ) minutes

D. ( 12.72 pm 0.77 ) minutes

Correct Answer: A

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Question 17

A particle of mass 2.0 ± 0.1 kg is moving in a circular path with a radius of 3.0 ± 0.1 m. If the particle experiences a centripetal acceleration of 4.0 ± 0.2 m/s², what is the magnitude of the net force acting on the particle?

Correct A. ( 12.0 pm 1.6 ) N

B. ( 16.0 pm 2.1 ) N

C. ( 20.0 pm 2.6 ) N

D. ( 24.0 pm 3.2 ) N

Correct Answer: A

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Question 18

A projectile is launched from the ground with an initial velocity of 20.0 ± 0.5 m/s at an angle of 30° above the horizontal. If the acceleration due to gravity is 9.8 ± 0.2 m/s², what is the maximum height reached by the projectile?

Correct A. ( 10.0 pm 0.5 ) m

B. ( 12.0 pm 0.6 ) m

C. ( 14.0 pm 0.7 ) m

D. ( 16.0 pm 0.8 ) m

Correct Answer: A

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Question 19

A 100 µF capacitor is connected in series with a 200 µF capacitor and a 500 µF resistor. If the circuit is driven by a 10 V AC source with a frequency of 50 Hz, what is the impedance of the circuit?

A. ( 150 µ Omega )

Correct B. ( 200 µ Omega )

C. ( 250 µ Omega )

D. ( 300 µ Omega )

Correct Answer: B

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Question 20

A 10 µF capacitor is connected in parallel with a 20 µF capacitor. If the circuit is driven by a 5 V AC source with a frequency of 60 Hz, what is the equivalent capaci\tance of the circuit?

A. ( 10 µ F )

B. ( 15 µ F )

Correct C. ( 20 µ F )

D. ( 25 µ F )

Correct Answer: C

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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 acceleration of 2 m/s^2, what is the magnitude of the 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 22

A 10 μF capacitor is connected in series with a 20 Ω resistor and a 50 V battery. If the switch is closed at t = 0, what is the time cons\tant of the circuit?

A. 0.1 s

Correct B. 0.2 s

C. 0.5 s

D. 1 s

Correct Answer: B

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Question 23

A wave of frequency 100 Hz and amplitude 2 m is traveling along a string. If the string is stretched to twice its original length, what is the new frequency of the wave?

A. 50 Hz

B. 75 Hz

C. 100 Hz

Correct D. 125 Hz

Correct Answer: D

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Question 24

A 5 kg block is attached to a horizontal spring with a force cons\tant of 100 N/m. If the block is displaced by 2 m from its equilibrium position and released, 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 25

A 10 μF capacitor is connected in parallel with a 20 μF capacitor. If a 50 V battery is connected across the combination, what is the equivalent capaci\tance?

A. 10 μF

B. 20 μF

Correct C. 30 μF

D. 40 μF

Correct Answer: C

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