JAMB Physics Past Questions 2020

10 questions from the JAMB 2020 Physics paper, with answers and explanations. Tap "Show answer" under each one when you are ready.

JAMB 2020Question 1 · Electricity and Magnetism

Which of the following can be described as high tension transmission?

A.High resistance and low voltage
B.Low current and high voltage
C.High current and low voltage
D.High current and low resistance

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Answer: B. Low current and high voltage

High-tension transmission uses high voltage with low current.

JAMB 2020Question 2 · Electricity and Magnetism

A magnetic needle is suspended first at the earth's north magnetic pole and then at a point on the magnetic equator. The respective angles between the needle and the horizontal are

A.0 $^{o}$ and 0 $^{o}$
B.60 $^{o}$ and 60 $^{o}$
C.90 $^{o}$ and 90 $^{o}$
D.90 $^{o}$ and 0 $^{o}$

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Answer: D. 90 $^{o}$ and 0 $^{o}$

The dip angle is $9 0^{\circ}$ at the magnetic pole and $0^{\circ}$ at the magnetic equator.

JAMB 2020Question 3 · General Physics and Measurement

One of the following readings represents the measurement of the length of a metal rod using vernier callipers. Taking the reading accuracy into consideration, the most likely one is

A. $5.16 cm$
B. $5.165 cm$
C. $5.0 cm$
D. $5.160 cm$

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Answer: A. $5.16 cm$

A vernier caliper reads to 2 decimal places ( $0.01 cm$ ), so $5.16 cm$ is the appropriate precision.

JAMB 2020Question 4 · Heat and Thermodynamics

In the study of Physics, temperature and heat are often confused with each other. Which of the following statements correctly defines these two elements?

A.Temperature is a measure of the average kinetic energy of the molecules of a substance
B.Heat is a measure of the total kinetic energy of the molecules in a system
C.Different materials require different amounts of heat to cause a given change in temperature
D.All of the above

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Answer: D. All of the above

All the statements correctly describe temperature and heat.

JAMB 2020Question 5 · Heat and Thermodynamics

Heat is supplied uniformly at the rate of

100 W

1.0 \times 1 0^{- 2}

kg of a liquid for 20 seconds. If the temperature of the liquid rises by 5

^{o}

C, then the specific heat capacity of the liquid is

A. $2.0 \times 1 0^{2}$ Jkg $^{-} 1$ $K^{- 1}$
B. $2.0 \times 1 0^{2}$ Jkg $^{-} 1$
C. $4.0 \times 1 0^{4}$ Jkg $^{-} 1$ $K^{- 1}$
D. $4.0 \times 1 0^{4}$ Jkg $^{-} 1$

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Answer: C. $4.0 \times 1 0^{4}$ Jkg $^{-} 1$ $K^{- 1}$

c=Q/(mdeltaT)=(100x20)/(0.01x5)= $4.0 \times 1 0^{4}$ J/kgK.

JAMB 2020Question 6 · Mechanics, Motion, and Energy

If in a simple pendulum experiment the length of the inextensible string is increased by a factor of four, its period is increased by a factor of?

A.4
B. $\frac{π}{2}$
C. $\frac{1}{4}$
D.2

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Answer: D. 2

T is proportional to $L$ ; quadrupling L doubles T.

JAMB 2020Question 7 · Nuclear and Modern Physics

Natural radioactivity consists of emission?

A. $α$ -particles and $β$ -rays
B. $α$ -particles and X-rays
C. $γ$ -ray and X-rays
D. $α$ -particles and $β$ -rays and $γ$ -rays

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Answer: D. $α$ -particles and $β$ -rays and $γ$ -rays

Natural radioactivity involves alpha particles, beta rays and gamma rays.

JAMB 2020Question 8 · Properties of Matter and Fluids

A few grains of table salt were put in a cup of cold water, kept at constant temperature and left undistributed. Eventually all the water tested salty. This action is due to?

A.convection
B.osmosis
C.capillarity
D.diffusion

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Answer: D. diffusion

Salt spreading through still water without stirring is due to diffusion.

JAMB 2020Question 9 · Waves, Sound, and Optics

When a sound wave passes from air into water its

A.speed and frequency increases but its wavelength remains the same
B.speed and wavelength increases but its frequency remains the same
C.speed decreases
D.speed increases but its frequency and wavelength decreases

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Answer: B. speed and wavelength increases but its frequency remains the same

In water, sound speed and wavelength increase while frequency stays the same.

JAMB 2020Question 10 · Waves, Sound, and Optics

A ship travelling towards a cliff receives the echo of its whistle after 3.5 seconds. A short while later, it receives the echo after 2.5 seconds. If the speed of sound in air under the prevalling condition is

250 m s^{- 1}

, how much closer is the ship to the cliff?

A. $10 m$
B. $350 m$
C. $175 m$
D. $125 m$

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Answer: D. $125 m$

Distances= $437.5 m$ and $312.5 m$ ; difference= $125 m$ .

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JAMB Physics Past Questions 2020

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