POST UTME GREENFIELD UNIVERSITY 2021 Physics | Objective

Practice these randomly selected questions to test your readiness.

Question 1
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 $K$?
A. \( K = \frac{Cd}{epsilon_0 A} \)
B. \( K = \frac{epsilon_0 A}{Cd} \)
C. \( K = \frac{Cd}{epsilon_0 A} + 1 \)
D. \( K = \frac{epsilon_0 A}{Cd} + 1 \)
Question 2
A magnetic field $B$ is directed perp\endicular to a current-carrying wire. What is the direction of the force $F$ on the wire?
A. perp\endicular to the current
B. parallel to the current
C. perp\endicular to the magnetic field
D. parallel to the magnetic field
Question 3
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 force?
A. 8 N
B. 12 N
C. 16 N
D. 20 N
Question 4
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
B. 1 J
C. 2 J
D. 5 J
Question 5
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
B. mvr
C. mv^2r
D. mv^2/r^2
Question 6
A ray of light passes through a prism and is re\fracted at an angle of 30°. If the angle of incidence is 20°, what is the angle of re\fraction?
A. 10°
B. 20°
C. 30°
D. 40°
Question 7
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.
A. 0.01 F
B. 0.02 F
C. 0.03 F
D. 0.04 F
Question 8
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
B. 1.8 m
C. 2 m
D. 2.1 m
Question 9
A particle of mass 2 kg is moving in a circular path of radius 3 m with a speed of 4 m/s. What is the centripetal force acting on the particle?
A. 10 N
B. 20 N
C. 30 N
D. 40 N
Question 10
A radioactive sample has a half-life of 10 years. If the initial activity is 100 Bq, calculate the activity after 20 years.
A. 12.5 Bq
B. 25 Bq
C. 50 Bq
D. 100 Bq
Question 11
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, what is the potential energy stored in the spring?
A. 100 J
B. 200 J
C. 300 J
D. 400 J
Question 12
A parallel plate capacitor has plates of area 0.04 m^2 and separation 0.02 m. If the capaci\tance is 8.0 µF, what is the value of the dielectric cons\tant?
A. 1.0
B. 2.0
C. 3.0
D. 4.0
Question 13
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?
A. 20°
B. 30°
C. 40°
D. 50°
Question 14
A 100 W light bulb is connected to a 220 V power source. What is the current drawn by the bulb?
A. 0.5 A
B. 1 A
C. 2 A
D. 5 A
Question 15
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. \( A = A + 1, Z = Z + 1 \)
B. \( A = A - 1, Z = Z + 1 \)
C. \( A = A + 1, Z = Z - 1 \)
D. \( A = A - 1, Z = Z - 1 \)

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