POST UTME IGBINEDION UNIVERSITY 2021 Physics | Objective

Practice these randomly selected questions to test your readiness.

Question 1
A radioactive sample has a half-life of 5 years. If the initial activity of the sample is 1000 Bq, what is the activity of the sample after 10 years?
A. 125 Bq
B. 250 Bq
C. 500 Bq
D. 1000 Bq
Question 2
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 acceleration of the particle?
A. 2 m/s^2
B. 4 m/s^2
C. 6 m/s^2
D. 8 m/s^2
Question 3
A block of mass $m$ is attached to a horizontal, massless spring with spring cons\tant $k$. The block is displaced from its equilibrium position by a dis\tance $x_0$ and released from rest. Assuming the motion is simple harmonic, find the period $T$ of the motion in terms of $m$, $k$, and $x_0$.
A. T = 2\pi \sqrt{\frac{k}{m}}
B. T = 2\pi \sqrt{\frac{m}{k}}
C. T = 2\pi \sqrt{\frac{k}{x_0}}
D. T = 2\pi \sqrt{\frac{x_0}{m}}
Question 4
A circuit consists of a 12 V battery, a 4 Ω resistor, and an inductor with induc\tance $L$. The circuit is connected to a switch that is initially open. At $t = 0$, the switch is closed. Find the current $I(t)$ in the circuit at time $t$.
A. I(t) = \frac{12}{4} \left\( 1 - e^{-\frac{t}{L}} \right \)
B. I(t) = \frac{12}{4} \left\( 1 + e^{-\frac{t}{L}} \right \)
C. I(t) = \frac{12}{4} \left\( 1 - e^{\frac{t}{L}} \right \)
D. I(t) = \frac{12}{4} \left\( 1 + e^{\frac{t}{L}} \right \)
Question 5
A parallel plate capacitor consists of two plates of area $A$ separated by a dis\tance $d$. The capaci\tance of the capacitor is given by $C = \frac{epsilon_0 A}{d}$. If the area of the plates is doubled and the dis\tance between them is halved, what is the new capaci\tance?
A. \frac{\epsilon_0 A}{d}
B. \frac{2\epsilon_0 A}{d}
C. \frac{\epsilon_0 (2A)}{d}
D. \frac{2\epsilon_0 A}{d/2}
Question 6
A particle of mass $m$ is moving in a circular orbit of radius $r$ with a speed $v$. If the particle is subject to a centripetal force $F_c = \frac{mv^2}{r}$, what is the magnitude of the acceleration of the particle?
A. \frac{v^2}{r}
B. \frac{mv^2}{r}
C. \frac{m}{r}
D. \frac{r}{m}
Question 7
A wave has a frequency of 50 Hz and a wavelength of 0.2 m. 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 10 Ω resistor is connected in series with a 20 Ω resistor and a 50 V battery. What is the current flowing through the 10 Ω resistor?
A. 1 A
B. 2 A
C. 3 A
D. 4 A
Question 9
A uniform magnetic field of magnitude 2.5 T is applied to a coil of 100 turns and radius 0.05 m. If the coil is rotated by 90° in 0.1 s, calculate the induced emf in the coil.
A. 0.25 V
B. 0.5 V
C. 1 V
D. 2 V
Question 10
A 100 W heater is used to heat a room. If the room has a volume of 100 m^3 and the temperature is 20°C, what is the rate of heat transfer?
A. 2000 J/s
B. 4000 J/s
C. 6000 J/s
D. 8000 J/s
Question 11
A gas expands from 1.5 L to 3 L against a cons\tant external pressure of 2 atm. If the initial temperature is 300 K, calculate the work done by the gas.
A. 120 J
B. 240 J
C. 360 J
D. 480 J
Question 12
A 2 kg block is attached to a horizontal spring with a force cons\tant of 100 N/m. If the block is displaced by 0.1 m and released, what is the maximum speed?
A. 0.5 m/s
B. 1.0 m/s
C. 2.0 m/s
D. 5.0 m/s
Question 13
A light wave of frequency $f$ is pas\sing through a medium of re\fractive index $n$. If the speed of the light wave in the medium is $v$, what is the wavelength of the light wave?
A. \frac{v}{f}
B. \frac{f}{v}
C. nf
D. \frac{1}{nf}
Question 14
A photon of energy 2.5 eV is incident on a metal surface with a work function of 1.5 eV. What is the maximum kinetic energy of the emitted electron?
A. 0.5 eV
B. 1.0 eV
C. 1.5 eV
D. 2.0 eV
Question 15
A radioactive sample has a half-life of 10 years. If the initial activity is 100 Bq, what is the activity after 20 years?
A. 25 Bq
B. 50 Bq
C. 100 Bq
D. 200 Bq

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