POST UTME ABU 2021 Physics | Objective

Practice these randomly selected questions to test your readiness.

Question 1
A ray of light passes from air into a glass slab of re\fractive index 1.5. If the angle of incidence is 30°, calculate the angle of re\fraction.
A. 20°
B. 25°
C. 30°
D. 35°
Question 2
A photon of energy 2 eV is incident on a metal surface. If the work function of the metal is 1.5 eV, what is the maximum kinetic energy of the emitted electron?
A. 0.5 eV
B. 1 eV
C. 1.5 eV
D. 2 eV
Question 3
A particle of mass 1 kg is moving in a circular path of radius 2 m with a cons\tant speed of 4 m/s. Calculate the magnitude of the force acting on the particle.
A. 10 N
B. 20 N
C. 30 N
D. 40 N
Question 4
A circuit consists of a resistor $R$, an inductor $L$, and a capacitor $C$ connected in series. If the circuit is driven by an AC voltage source with frequency $f$, what is the impedance of the circuit?
A. \sqrt{R^2 + \( \omega L - \frac{1}{\omega C} \)^2}
B. \sqrt{R^2 + \( \omega L + \frac{1}{\omega C} \)^2}
C. \sqrt{R^2 + \( \omega L - \frac{1}{\omega C} \)^2}
D. \sqrt{R^2 + \( \omega L + \frac{1}{\omega C} \)^2}
Question 5
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. 12.5\,Bq
B. 25\,Bq
C. 50\,Bq
D. 100\,Bq
Question 6
A gas is enclosed in a container with a movable piston. The gas is heated, cau\sing its pressure to increase. Which of the following statements is true about the behavior of the gas?
A. The gas expands to fill the container.
B. The gas contracts to occupy less space.
C. The gas remains at cons\tant pressure.
D. The gas undergoes a phase transition.
Question 7
A particle of mass $m$ is moving in a circular path of radius $r$ with a cons\tant speed $v$. The particle is subject to a centripetal force $F_c$ given by $F_c = \frac{mv^2}{r}$. If the particle's speed is doubled, what happens to the centripetal force?
A. The centripetal force remains the same.
B. The centripetal force increases by a factor of 2.
C. The centripetal force increases by a factor of 4.
D. The centripetal force decreases by a factor of 2.
Question 8
A spring with a force cons\tant of 200 N/m is stretched by 0.1 m. Calculate the work done in stretching the spring.
A. 2 J
B. 4 J
C. 6 J
D. 8 J
Question 9
A simple harmonic motion has a period $T$ and amplitude $A$. If the motion is damped by a force proportional to the velocity, what is the equation of motion?
A. x(t) = A\cos\( \omega t - \phi \)
B. x(t) = A\sin\( \omega t - \phi \)
C. x(t) = A\cos\( \omega t + \phi \)
D. x(t) = A\sin\( \omega t + \phi \)
Question 10
A particle of mass $m$ is moving in a circular path of radius $r$ with a cons\tant speed $v$. The particle experiences a centripetal force $F_c$ given by $F_c = \frac{mv^2}{r}$. If the particle's speed is doubled to $2v$, what is the new centripetal force $F_{c,new}$?
A. \frac{2mv^2}{r}
B. \frac{mv^2}{2r}
C. \frac{mv^2}{r}
D. \frac{mv^2}{4r}
Question 11
A car is traveling at a cons\tant speed of 50 km/h. If the driver applies the brakes, cau\sing the car to decelerate at 2 m/s^2, what is the time taken for the car to come to rest?
A. 10 s
B. 20 s
C. 30 s
D. 40 s
Question 12
A radioactive sample has a half-life of 5 years. If the initial activity of the sample is 100 Bq, what is the activity of the sample after 10 years?
A. 50 Bq
B. 25 Bq
C. 12.5 Bq
D. 6.25 Bq
Question 13
A 10 Ω resistor is connected in series with a 20 Ω resistor and a 30 Ω resistor. If a voltage of 12 V is applied across the circuit, what is the current flowing through the 10 Ω resistor?
A. 0.4 A
B. 0.6 A
C. 0.8 A
D. 1 A
Question 14
A block of mass $m$ is attached to a horizontal spring with spring cons\tant $k$. If the block is displaced by a dis\tance $x$ from its equilibrium position and released, what is the maximum speed of the block?
A. \sqrt{\frac{kx^2}{m}}
B. \sqrt{\frac{mx^2}{k}}
C. \sqrt{\frac{k}{m}}
D. \sqrt{\frac{m}{k}}
Question 15
A point charge $q$ is placed at the center of a spherical shell of radius $R$. If a test charge $Q$ is placed at a dis\tance $r$ from the center of the shell, what is the electric potential at the location of the test charge?
A. \frac{1}{4\pi\epsilon_0}\frac{q}{r}
B. \frac{1}{4\pi\epsilon_0}\frac{q}{R}
C. \frac{1}{4\pi\epsilon_0}\frac{Q}{r}
D. \frac{1}{4\pi\epsilon_0}\frac{Q}{R}

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