POST UTME RHEMA UNIVERSITY 2020 Physics | Objective

Practice these randomly selected questions to test your readiness.

Question 1
A parallel plate capacitor consists of two plates, each of area $A$ and separation $d$. The space between the plates is filled with a dielectric material of dielectric cons\tant $K$. If a potential difference of $V$ is applied across the plates, calculate the capaci\tance $C$ of the capacitor.
A. C = \frac{KA\epsilon_0}{d}
B. C = \frac{KA\epsilon_0}{d^2}
C. C = \frac{KA}{d}
D. C = \frac{KA\epsilon_0}{d^3}
Question 2
A charged particle of mass $m$ and charge $q$ is moving in a circular path of radius $R$ in a uniform magnetic field of strength $B$. If the particle's speed is $v$, what is the magnitude of the magnetic field?
A. \frac{mv}{qR}
B. \frac{qR}{mv}
C. \frac{mv^2}{qR}
D. \frac{qR^2}{mv}
Question 3
A simple harmonic motion is described by the equation $x(t) = A \cos\( \omega t + \phi \)$, where $A$ is the amplitude, $\omega$ is the angular frequency, and $\phi$ is the phase angle. If the particle is at the equilibrium position at $t = 0$, what is the phase angle?
A. 0
B. \frac{\pi}{2}
C. \pi
D. \frac{3\pi}{2}
Question 4
A capacitor consists of two parallel plates separated by a dis\tance of 2 mm. If the capaci\tance of the capacitor is 10 μF, what is the charge stored on the capacitor when a potential difference of 5 V is applied across it?
A. 50 μC
B. 100 μC
C. 150 μC
D. 200 μC
Question 5
A lens of focal length 20 cm forms an image of an object at a dis\tance of 30 cm. What is the magnification of the lens?
A. 0.5
B. 1
C. 2
D. 3
Question 6
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 15 days?
A. 12.5 Bq
B. 25 Bq
C. 50 Bq
D. 100 Bq
Question 7
A wave has a frequency of 50 Hz and a wavelength of 0.2 m. If the wave is traveling in the positive x-direction, what is the speed of the wave?
A. 10 m/s
B. 20 m/s
C. 30 m/s
D. 40 m/s
Question 8
A gas is confined to a cylinder of volume 0.1 m^3 at a temperature of 300 K. If the gas is heated to a temperature of 400 K, calculate the new volume of the gas.
A. 0.2 m^3
B. 0.3 m^3
C. 0.4 m^3
D. 0.5 m^3
Question 9
A sound wave has a frequency of 200 Hz and a speed of 340 m/s. If the wave is traveling in the positive x-direction, what is the wavelength of the wave?
A. 1.7 m
B. 1.8 m
C. 1.9 m
D. 2.0 m
Question 10
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 net force acting on the particle?
A. 8 N
B. 12 N
C. 16 N
D. 20 N
Question 11
A particle of mass $m$ is moving in a circular path of radius $r$ with a cons\tant speed $v$. If the particle experiences a centripetal force $F_c = \frac{mv^2}{r}$, what is the magnitude of the force?
A. \frac{mv^2}{r}
B. \frac{mv}{r}
C. \frac{m}{r}
D. \frac{v}{r}
Question 12
A sound wave with a frequency of 200 Hz is traveling through a medium with a speed of 340 m/s. What is the wavelength of the sound wave?
A. 1.7 m
B. 1.7 cm
C. 1.7 km
D. 1.7 μm
Question 13
A point charge is placed at the center of a spherical conductor. What will happen to the electric field inside the conductor?
A. The electric field will increase.
B. The electric field will decrease.
C. The electric field will remain cons\tant.
D. The electric field will become zero.
Question 14
A radioactive sample decays according to the equation $N(t) = N_0 e^{-\lambda t}$, where $N_0$ is the initial number of nuclei, $\lambda$ is the decay cons\tant, and $t$ is time. If the sample decays to $\frac{1}{4}$ of its initial value in 10 minutes, what is the decay cons\tant?
A. \frac{1}{10} \text{min}^{-1}
B. \frac{1}{20} \text{min}^{-1}
C. \frac{1}{30} \text{min}^{-1}
D. \frac{1}{40} \text{min}^{-1}
Question 15
A charged particle is moving through a magnetic field. If the particle is positively charged, what will happen to its path?
A. The particle will be deflected towards the magnetic field.
B. The particle will be deflected away from the magnetic field.
C. The particle will not be deflected.
D. The particle will be accelerated.

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