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POST UTME GREENFIELD UNIVERSITY 2021 Physics | Objective

Are you preparing for POST UTME GREENFIELD UNIVERSITY exams? Reviewing past questions is one of the most effective ways to guarantee a high score. This practice hub features authentic 2021 Physics (Objective) questions designed to simulate the real exam environment.

Practice these randomly selected questions to test your readiness.

Question 1

A particle of mass $m$ is moving in a circular orbit of radius $r$ under the influence of a central force given by $F(r) = -\frac{k}{r^2}$. If the particle's speed is $v$, what is its angular momentum $L$?

A. mv^2/r

Correct B. mvr

C. mv^2r

D. mv^2/r^2

Correct Answer: B

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Question 2

A capacitor consists of two parallel plates, each of area $A$ and separated by a dis\tance $d$. The plates are charged to a potential difference $V$. What is the capaci\tance $C$?

Correct A. \frac{\epsilon_0 A}{d}

B. \frac{\epsilon_0 A}{V}

C. \frac{V}{\epsilon_0 A}

D. \frac{d}{\epsilon_0 A}

Correct Answer: A

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Question 3

A sound wave with frequency $f$ and amplitude $A$ is traveling through a medium with speed $v$. What is the wavelength $\lambda$?

Correct A. v/f

B. f/v

C. Av/f

D. v/Af

Correct Answer: A

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Question 4

A magnetic field $B$ is directed perp\endicular to a current-carrying wire. What is the direction of the force $F$ on the wire?

Correct A. perp\endicular to the current

B. parallel to the current

C. perp\endicular to the magnetic field

D. parallel to the magnetic field

Correct Answer: A

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Question 5

A quantum particle is confined to a one-dimensional box of length $L$. What is the ground-state energy $E_1$?

Correct A. h^2/$ 8mL^2 $

B. h^2/$ 4mL^2 $

C. h^2/$ 2mL^2 $

D. h^2/$ mL^2 $

Correct Answer: A

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Question 6

A parallel plate capacitor has plates of area $A$ and separation $d$. If the capaci\tance is $C$, what is the value of the dielectric cons\tant $K$?

Correct A. $ K = \frac{Cd}{epsilon_0 A} $

B. $ K = \frac{epsilon_0 A}{Cd} $

C. $ K = \frac{Cd}{epsilon_0 A} + 1 $

D. $ K = \frac{epsilon_0 A}{Cd} + 1 $

Correct Answer: A

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Question 7

A magnetic field is produced by a current-carrying wire. If the current is $I$ and the wire has a radius of $r$, what is the magnitude of the magnetic field at a dis\tance $x$ from the wire?

Correct A. $ B = \frac{mu_0 I}{2 pi x} $

B. $ B = \frac{mu_0 I x}{2 pi r^2} $

C. $ B = \frac{mu_0 I r^2}{2 pi x^2} $

D. $ B = \frac{mu_0 I x^2}{2 pi r^2} $

Correct Answer: A

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Question 8

A nucleus has a mass number of $A$ and an atomic number of $Z$. If the nucleus undergoes \beta decay, what is the resulting nucleus?

A. $ A = A + 1, Z = Z + 1 $

Correct B. $ A = A - 1, Z = Z + 1 $

C. $ A = A + 1, Z = Z - 1 $

D. $ A = A - 1, Z = Z - 1 $

Correct Answer: B

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Question 9

A gas is heated from $T_1$ to $T_2$. If the initial volume is $V_1$ and the final volume is $V_2$, what is the ratio of the final volume to the initial volume?

Correct A. $ \frac{V_2}{V_1} = \frac{T_2}{T_1} $

B. $ \frac{V_2}{V_1} = \frac{T_1}{T_2} $

C. $ \frac{V_2}{V_1} = \frac{T_2 - T_1}{T_1} $

D. $ \frac{V_2}{V_1} = \frac{T_1 - T_2}{T_2} $

Correct Answer: A

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Question 10

A heat engine operates between two temperatures $T_1$ and $T_2$. If the efficiency of the engine is $eta$, what is the ratio of the work done to the heat input?

Correct A. $ \frac{W}{Q} = eta $

B. $ \frac{W}{Q} = 1 - eta $

C. $ \frac{W}{Q} = \frac{T_1 - T_2}{T_1} $

D. $ \frac{W}{Q} = \frac{T_2 - T_1}{T_2} $

Correct Answer: A

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Question 11

A particle of mass 2 kg is attached to a spring with spring cons\tant 100 N/m. If the particle is displaced by 0.2 m from its equilibrium position and released from rest, determine the angular frequency of the resulting simple harmonic motion.

A. 10 rad/s

Correct B. 20 rad/s

C. 30 rad/s

D. 40 rad/s

Correct Answer: B

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Question 12

A sound wave with frequency 200 Hz and amplitude 0.05 m is traveling through a medium with speed 340 m/s. If the wave is reflected off a rigid boundary, determine the intensity of the reflected wave.

A. 0.1 W/m^2

Correct B. 0.2 W/m^2

C. 0.3 W/m^2

D. 0.4 W/m^2

Correct Answer: B

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Question 13

A capacitor consists of two parallel plates, each with area 0.1 m^2 and separated by a dis\tance 0.01 m. If the plates are charged to a potential difference of 10 V, determine the capaci\tance of the capacitor.

Correct A. 0.01 F

B. 0.02 F

C. 0.03 F

D. 0.04 F

Correct Answer: A

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Question 14

A circuit consists of a 12 V battery, a 4 Ω resistor, and a 2 H inductor in series. If the circuit is closed at time t = 0, determine the current in the circuit at time t = 2 s.

A. 2 A

B. 3 A

Correct C. 4 A

D. 5 A

Correct Answer: C

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Question 15

A block of mass 5 kg is attached to a spring with spring cons\tant 200 N/m. If the block is displaced by 0.1 m from its equilibrium position and released from rest, determine the maximum kinetic energy of the block.

A. 0.5 J

B. 1 J

Correct C. 1.5 J

D. 2 J

Correct Answer: C

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Question 16

A beam of light is incident on a glass slab at an angle of 45°. If the re\fractive index of the glass is 1.5, calculate the angle of re\fraction.

Correct A. 30°

B. 45°

C. 60°

D. 75°

Correct Answer: A

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Question 17

A radioactive sample has a half-life of 10 years. If the initial activity is 100 Bq, calculate the activity after 20 years.

Correct A. 12.5 Bq

B. 25 Bq

C. 50 Bq

D. 100 Bq

Correct Answer: A

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Question 18

A particle of mass 2 kg is attached to a spring with a spring cons\tant of 100 N/m. If the particle is displaced by 0.5 m from its equilibrium position and released, calculate the maximum kinetic energy of the particle.

A. 0.5 J

Correct B. 1 J

C. 2 J

D. 5 J

Correct Answer: B

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Question 19

A sound wave with a frequency of 200 Hz has a speed of 340 m/s. Calculate the wavelength of the sound wave.

A. 1.7 m

Correct B. 1.8 m

C. 2 m

D. 2.1 m

Correct Answer: B

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Question 20

A light beam is incident on a prism at an angle of 30°. If the re\fractive index of the prism is 1.5, calculate the angle of deviation.

A. 10°

Correct B. 20°

C. 30°

D. 40°

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 experiences a centripetal acceleration of 2 m/s^2, what is the force exerted on the particle?

A. 8 N

Correct B. 16 N

C. 32 N

D. 64 N

Correct Answer: B

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Question 22

A light ray passes from air into a glass slab of re\fractive index 1.5. If the angle of incidence is 30°, what is the angle of re\fraction?

Correct A. 20°

B. 30°

C. 40°

D. 50°

Correct Answer: A

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Question 23

A radioactive sample has a half-life of 5 years. If the initial activity is 100 Bq, what is the activity after 10 years?

Correct A. 12.5 Bq

B. 25 Bq

C. 50 Bq

D. 100 Bq

Correct Answer: A

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Question 24

A simple harmonic motion has a maximum displacement of 2 m and a period of 4 s. What is the angular frequency?

A. 1.57 rad/s

Correct B. 3.14 rad/s

C. 6.28 rad/s

D. 12.56 rad/s

Correct Answer: B

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Question 25

A light source is placed 2 m away from a convex lens of focal length 0.5 m. If the image dis\tance is 1.5 m, what is the object dis\tance?

A. 0.5 m

B. 1 m

Correct C. 1.5 m

D. 2 m

Correct Answer: C

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