POST UTME REDEEMERS UNIVERSITY 2021 Physics | Objective

Practice these randomly selected questions to test your readiness.

Question 1
A 2.5 m long wire is made of a material with a resistivity of 2.1 × 10^\( -8 \) Ωm. If the wire is stretched to a length of 5 m, what is the new resis\tance?
A. 1.05 × 10^\( -7 \) Ω
B. 2.1 × 10^\( -7 \) Ω
C. 4.2 × 10^\( -7 \) Ω
D. 5.25 × 10^\( -7 \) Ω
Question 2
A charged particle of mass 1.6 x 10^-19 C and charge 2.0 x 10^-19 C is moving in a magnetic field of strength 0.5 T. If the particle has a velocity of 3.0 x 10^5 m/s, what is the magnitude of the force acting on the particle?
A. 1.2 x 10^-14 N
B. 1.2 x 10^-13 N
C. 1.2 x 10^-12 N
D. 1.2 x 10^-11 N
Question 3
A charged particle of mass $m$ and charge $q$ is moving in a uniform magnetic field $\vec{B}$. If the particle is moving in a circular path of radius $R$, what is the speed of the particle?
A. \frac{qBR}{m}
B. \frac{qB}{m}
C. \frac{m}{qB}
D. \frac{q}{mB}
Question 4
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. 6 m/s^2
B. 8 m/s^2
C. 10 m/s^2
D. 12 m/s^2
Question 5
A projectile is launched from the origin with an initial velocity $v_0$ at an angle $\theta$ above the horizontal. What is the maximum height reached by the projectile?
A. \( \frac{v_0^2 \sin^2 \theta}{2g} \)
B. \( \frac{v_0^2 \cos^2 \theta}{2g} \)
C. \( \frac{v_0^2 \sin \theta}{2g} \)
D. \( \frac{v_0^2 \cos \theta}{2g} \)
Question 6
A tuning fork of frequency 256 Hz is placed in a stationary air column. If the speed of sound in air is 343 m/s, what is the wavelength of the sound wave produced by the tuning fork?
A. 1.34 m
B. 1.34 cm
C. 1.34 km
D. 1.34 μm
Question 7
A lens with a focal length of 0.2 m is used to form an image of an object 0.5 m away. What is the magnification of the lens?
A. 2
B. 3
C. 4
D. 5
Question 8
A 100 W heater is connected to a 230 V AC supply. If the current is 0.5 A, what is the power factor?
A. 0.5
B. 0.6
C. 0.7
D. 0.8
Question 9
A 5.0 mH inductor is connected in series with a 2.0 Ω resistor and a 12 V battery. If the initial current is 0 A, what is the current after 0.2 s?
A. 0.5 A
B. 1.0 A
C. 1.5 A
D. 2.0 A
Question 10
A 2.0 mH inductor is connected in series with a 3.0 Ω resistor and a 12 V battery. If the initial current is 0 A, what is the current after 0.1 s?
A. 0.5 A
B. 1.0 A
C. 1.5 A
D. 2.0 A
Question 11
A particle of mass $m$ is moving in a circular orbit of radius $r$ with a cons\tant speed $v$. What is the magnitude of the centripetal acceleration of the particle?
A. \( \frac{v^2}{r} \)
B. \( \frac{r^2}{v} \)
C. \( \frac{v}{r} \)
D. \( \frac{r}{v} \)
Question 12
A wave of frequency $f$ and wavelength $lambda$ is traveling through a medium with speed $v$. What is the angular frequency of the wave?
A. ( 2pi f )
B. \( \frac{2pi f}{lambda} \)
C. \( \frac{lambda}{2pi f} \)
D. \( \frac{v}{2pi f} \)
Question 13
A particle moves in a circular path with a radius of 2 m. If it completes one revolution in 4 s, what is its angular velocity?
A. 0.5 rad/s
B. 1 rad/s
C. 2 rad/s
D. 4 rad/s
Question 14
A convex lens of focal length 20 cm is placed in contact with a concave lens of focal length -15 cm. What is the focal length of the combination?
A. 10 cm
B. 15 cm
C. 20 cm
D. 25 cm
Question 15
A heat engine operates between the temperatures 500 K and 300 K. If the heat engine absorbs 1000 J of heat from the high-temperature reservoir, what is the efficiency of the engine?
A. 0.25
B. 0.30
C. 0.35
D. 0.40

Master the Exam!

You've seen a preview, but there are thousands more questions plus AI tutor to break down complex solutions.

Unlock Full Access Available for Android & Windows
Help others prepare! Share this practice hub: