POST UTME ELIZADE UNIVERSITY 2019 Physics | Objective

Practice these randomly selected questions to test your readiness.

Question 1
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?
A. 50 Bq
B. 25 Bq
C. 12.5 Bq
D. 6.25 Bq
Question 2
A particle of mass 0.5 kg is moving in a circular path of radius 2 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 3
A particle of mass $m$ is moving in a circular orbit of radius $r$ with a speed $v$. If the particle is then placed in a uniform magnetic field of strength $B$, what is the magnitude of the magnetic force $F_B$ acting on the particle?
A. \frac{mv^2}{r}
B. \frac{mv^2}{r^2}
C. qvB
D. \frac{q^2v^2}{r^2}
Question 4
A particle of mass $m$ is moving in a circular path of radius $R$ with a cons\tant speed $v$. The particle is subjected to a centripetal force $F_c = \frac{mv^2}{R}$. If the particle is moving in a clockwise direction, what is the direction of the magnetic field $B$?
A. Into the page
B. Out of the page
C. Perp\endicular to the plane of the page
D. Parallel to the plane of the page
Question 5
A simple harmonic motion has an amplitude of $A = 2.0, \text{m}$ and a frequency of $f = 3.0, \text{Hz}$. If the motion is described by the equation $x(t) = A \cos\( omega t + phi \)$, what is the phase angle $phi$?
A. $0^circ$
B. $30^circ$
C. $60^circ$
D. $90^circ$
Question 6
A point charge of +2 μC is placed at the origin. A second point charge of -3 μC is placed 0.5 m away from the first charge. What is the electric potential at a point 0.2 m away from the second charge?
A. 100 V
B. 200 V
C. 300 V
D. 400 V
Question 7
A wave with a frequency of 50 Hz and a wavelength of 0.5 m is traveling through a medium. What is the speed of the wave?
A. 10 m/s
B. 20 m/s
C. 25 m/s
D. 30 m/s
Question 8
A 2 kg block is attached to a horizontal, massless spring with a force cons\tant of 100 N/m. The block is displaced by 0.2 m from its equilibrium position and released from rest. What is the maximum speed of the block?
A. 0.5 m/s
B. 1 m/s
C. 1.5 m/s
D. 2 m/s
Question 9
A light source is placed 2 m away from a convex lens of focal length 0.5 m. What is the image dis\tance?
A. 1 m
B. 2 m
C. 3 m
D. 4 m
Question 10
A heat engine operates between two temperatures $T_1 = 500, \text{K}$ and $T_2 = 300, \text{K}$. If the engine has an efficiency of $eta = 30%$, what is the temperature of the hot reservoir?
A. $500, \text{K}$
B. $550, \text{K}$
C. $600, \text{K}$
D. $650, \text{K}
Question 11
A circuit consists of a resistor $R$ and an inductor $L$ connected in series. If the circuit is driven by a voltage source of electromotive force $V$ and the circuit is initially at rest, what is the current $I$ in the circuit at time $t$?
A. \frac{V}{R}e^{-\frac{Rt}{L}}
B. \frac{V}{\sqrt{R^2+\omega^2L^2}}e^{-\frac{Rt}{L}}\sin\( \omega t-\frac{Rt}{L} \)
C. \frac{V}{R}e^{-\frac{\omega t}{L}}
D. \frac{V}{\sqrt{R^2+\omega^2L^2}}e^{-\frac{\omega t}{L}}\sin\( \omega t-\frac{\omega t}{L} \)
Question 12
A beam of light is incident on a prism of re\fracting angle $\alpha$ at an angle of incidence $\theta_1$. If the angle of re\fraction $\theta_2$ is measured to be $\theta_2$, what is the angle of deviation $\delta$ in terms of the angle of incidence $\theta_1$?
A. \delta=\alpha+\theta_1-\theta_2
B. \delta=\alpha-\theta_1+\theta_2
C. \delta=\alpha+\theta_1+\theta_2
D. \delta=\alpha-\theta_1-\theta_2
Question 13
A gas expands from 1.5 L to 2.5 L against a cons\tant external pressure of 2 atm. What is the work done by the gas?
A. 10 J
B. 20 J
C. 30 J
D. 40 J
Question 14
A current of 2 A flows through a wire of resis\tance 10 Ω. What is the power dissipated in the wire?
A. 20 W
B. 40 W
C. 60 W
D. 80 W
Question 15
A radioactive sample has an initial activity of $A_0 = 100, \text{Bq}$. If the sample decays with a half-life of $t_{1/2} = 10, \text{min}$, what is the activity of the sample after $t = 30, \text{min}$?
A. $20, \text{Bq}$
B. $30, \text{Bq}$
C. $40, \text{Bq}$
D. $50, \text{Bq}

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