POST UTME COAL CITY UNIVERSITY 2023 Physics | Objective

Practice these randomly selected questions to test your readiness.

Question 1
A parallel plate capacitor has plates of area 0.04 m^2 and separation 0.02 m. If the capaci\tance is 2.5 x 10^-10 F, what is the charge on the plates when the potential difference is 10 V?
A. 1.25 x 10^-9 C
B. 2.5 x 10^-9 C
C. 5 x 10^-9 C
D. 7.5 x 10^-9 C
Question 2
A sound wave with frequency 200 Hz and amplitude 0.05 m is traveling through a medium with speed 340 m/s. What is the intensity of the sound wave?
A. 1.4 x 10^-3 W/m^2
B. 2.8 x 10^-3 W/m^2
C. 4.2 x 10^-3 W/m^2
D. 5.6 x 10^-3 W/m^2
Question 3
A particle of mass $m$ is moving in a circular orbit of radius $r$ with a speed $v$. If the particle is suddenly subjected to a centripetal force $F_c = k \frac{v^2}{r}$, where $k$ is a cons\tant, what is the new speed of the particle?
A. \( v = \sqrt{\frac{k m r}{k - 1}} \)
B. \( v = \sqrt{\frac{k m r}{k + 1}} \)
C. \( v = \sqrt{\frac{k m r}{k - 2}} \)
D. \( v = \sqrt{\frac{k m r}{k + 2}} \)
Question 4
A 2.5 m long wire has a resis\tance of 3.2 Ω. If a potential difference of 12 V is applied across it, what is the current flowing through it?
A. 2.5 A
B. 3.2 A
C. 4.8 A
D. 6.4 A
Question 5
A circuit consists of a resistor $R$ and an inductor $L$ connected in series. If the circuit is driven by a \sinusoidal voltage source of frequency $f$ and amplitude $V_0$, what is the impedance of the circuit?
A. \( Z = \sqrt{R^2 + \( \omega L \)^2} \)
B. \( Z = \sqrt{R^2 - \( \omega L \)^2} \)
C. \( Z = R + \omega L \)
D. \( Z = R - \omega L \)
Question 6
A wave of wavelength $\lambda$ and frequency $f$ is traveling through a medium with a speed $v$. If the wave is reflected from a fixed \end, what is the magnitude of the resulting s\tanding wave?
A. \(\frac{2A_0}{\lambda} \sin \left\( \frac{2\pi x}{\lambda} \right \)
B. \(\frac{A_0}{\lambda} \sin \left\( \frac{2\pi x}{\lambda} \right \)
C. \(\frac{2A_0}{\lambda} \cos \left\( \frac{2\pi x}{\lambda} \right \)
D. \(\frac{A_0}{\lambda} \cos \left\( \frac{2\pi x}{\lambda} \right \)
Question 7
A 2.5 kg block is attached to a horizontal, massless spring with a force cons\tant of 100 N/m. If the block is displaced by 0.15 m from its equilibrium position and released from rest, determine the speed of the block when it passes through the equilibrium position.
A. 0.5 m/s
B. 1.0 m/s
C. 1.5 m/s
D. 2.0 m/s
Question 8
A particle is projected from the origin with an initial velocity of 20 m/s at an angle of 60° to the horizontal. What is the time of flight?
A. 1.5 s
B. 2.0 s
C. 2.5 s
D. 3.0 s
Question 9
A magnetic field of 0.5 T is applied to a coil of 100 turns. If the area of the coil is 0.01 m^2, what is the magnetic flux?
A. 0.005 Wb
B. 0.01 Wb
C. 0.015 Wb
D. 0.02 Wb
Question 10
A 10 Ω resistor is connected in series with a 20 V battery. If the current through the resistor is 0.2 A, what is the power dissipated by the resistor?
A. 2 W
B. 4 W
C. 6 W
D. 8 W
Question 11
A beam of light of wavelength $\lambda$ is incident on a dif\fraction grating with $N$ slits. If the first-order maximum occurs at an angle $\theta$, what is the condition for constructive interference?
A. \( d \sin\( \theta \) = m \lambda \)
B. \( d \sin\( \theta \) = n \lambda \)
C. \( d \sin\( \theta \) = \frac{m \lambda}{2} \)
D. \( d \sin\( \theta \) = \frac{n \lambda}{2} \)
Question 12
A 100 W heater is connected to a 230 V AC supply. If the power factor is 0.8, what is the current drawn?
A. 0.5 A
B. 0.6 A
C. 0.7 A
D. 0.8 A
Question 13
A heat engine operates between a high-temperature reservoir at 500°C and a low-temperature reservoir at 100°C. If the engine has an efficiency of 30%, determine the work output per cycle.
A. 200 J
B. 400 J
C. 600 J
D. 800 J
Question 14
A particle of mass $m$ is moving in a circular orbit of radius $R$ with a speed $v$. If the particle is subjected to a uniform magnetic field of strength $B$, what is the magnitude of the magnetic force acting on the particle?
A. \(\frac{mv^2}{R}\)
B. \(\frac{mv}{R}\)
C. \(\frac{m^2v^2}{R^2}\)
D. \(\frac{mv^2}{R^2}\)
Question 15
A 10 μF capacitor is connected in series with a 20 Ω resistor. If a potential difference of 12 V is applied across the circuit, what is the current flowing through the resistor?
A. 0.6 A
B. 0.8 A
C. 1.0 A
D. 1.2 A

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