Modern Physics Practice Questions
NECO (Nigeria) · NECO Physics · 147 free MCQs with instant results and detailed explanations.
147
Total
51
Easy
78
Medium
18
Hard
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Sample Questions from Modern Physics
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Q1
Easy
What is the principle behind the photoelectric effect?
A.
Light waves can transfer energy to electrons.
B.
Electrons can absorb any amount of energy.
C.
Electrons are emitted when light interacts with a metal surface.
D.
Light can be converted into sound energy.
Show Answer & Explanation
Correct Answer: C
The photoelectric effect demonstrates that when light strikes a metal surface, it can eject electrons from that surface, provided the light's frequency is above a certain threshold. This shows that light has particle-like properties.
Q2
Easy
In a nuclear reaction, which quantity is conserved?
A.
Mass only
B.
Energy only
C.
Charge and mass
D.
Momentum only
Show Answer & Explanation
Correct Answer: C
In nuclear reactions, both charge and mass are conserved. This means that the total charge before the reaction equals the total charge after the reaction, and the total mass-energy remains constant according to the principle of conservation.
Q3
Easy
What is the main application of semiconductors in modern electronics?
A.
They can easily conduct electricity.
B.
They can amplify electrical signals.
C.
They are used to store large amounts of data.
D.
They generate electricity from heat.
Show Answer & Explanation
Correct Answer: B
Semiconductors are crucial in electronics because they can control the flow of electricity and amplify electrical signals. This property makes them essential in transistors and integrated circuits.
Q4
Medium
What phenomenon explains the emission of electrons from metals when light shines on them?
A.
Photoelectric effect
B.
Compton effect
C.
Doppler effect
D.
Thermal emission
Show Answer & Explanation
Correct Answer: A
The photoelectric effect occurs when light hits a metal surface, causing it to emit electrons. This is a key concept in modern physics, demonstrating the particle-like behavior of light.
Q5
Medium
A photon has a frequency of 5 x 10^14 Hz. What is its energy?
A.
3.31 x 10^-19 J
B.
2.00 x 10^-19 J
C.
6.63 x 10^-19 J
D.
4.14 x 10^-19 J
Show Answer & Explanation
Correct Answer: C
The energy of a photon can be calculated using the formula E = hf, where h is Planck's constant (6.63 x 10^-34 Jยทs) and f is the frequency. Substituting the given frequency results in 6.63 x 10^-19 J.
Q6
Medium
Which of the following statements is true regarding nuclear fission?
A.
It involves the splitting of a heavy nucleus into smaller nuclei.
B.
It requires extremely high temperatures.
C.
It is a reaction that produces no energy.
D.
It occurs only in stable isotopes.
Show Answer & Explanation
Correct Answer: A
Nuclear fission is the process where a heavy nucleus splits into smaller nuclei along with the release of energy. This process is fundamental in nuclear reactors and weaponry.
Q7
Medium
What determines the stability of a nucleus?
A.
The ratio of protons to neutrons
B.
The total number of nucleons
C.
The type of electromagnetic radiation emitted
D.
The speed of the nucleus
Show Answer & Explanation
Correct Answer: A
The stability of a nucleus is largely determined by the ratio of protons to neutrons. An optimal ratio helps balance the repulsive forces among protons and the attractive forces from the strong nuclear force.
Q8
Hard
A radioactive isotope has a half-life of 10 years. If you start with 160 grams of this isotope, how much will remain after 30 years?
A.
20 grams
B.
40 grams
C.
80 grams
D.
10 grams
Show Answer & Explanation
Correct Answer: A
The remaining amount of a radioactive substance after a certain time can be calculated using the formula: Remaining amount = Initial amount ร (1/2)^(time/half-life). After 30 years, which is 3 half-lives (30/10), the calculation will be: 160 grams ร (1/2)^3 = 160 grams ร 1/8 = 20 grams. Thus, after 30 years, 20 grams of the isotope will remain.
Q9
Hard
A particle is in a one-dimensional infinite potential well of width 1 nm. What is the energy of the first excited state of the particle? (h = 6.626 x 10^-34 Jยทs, m = mass of the particle = 9.11 x 10^-31 kg)
A.
1.5 x 10^-18 J
B.
2.0 x 10^-18 J
C.
6.0 x 10^-19 J
D.
3.1 x 10^-18 J
Show Answer & Explanation
Correct Answer: C
The energy levels for a particle in an infinite potential well are given by the formula En = n^2 * ฯ^2 * h^2 / (2 * m * L^2). For the first excited state (n=2), E2 = (2^2 * ฯ^2 * (6.626 x 10^-34)^2) / (2 * 9.11 x 10^-31 * (1 x 10^-9)^2). Calculating gives E2 โ 6.0 x 10^-19 J.
Q10
Hard
A photon of energy 2.0 eV collides with a material and causes the emission of an electron. If the work function of the material is 1.5 eV, what is the maximum kinetic energy of the emitted electron?
A.
0.5 eV
B.
1.5 eV
C.
2.0 eV
D.
3.5 eV
Show Answer & Explanation
Correct Answer: A
The maximum kinetic energy of the emitted electron can be found using the equation: K.E = E - W, where E is the energy of the photon and W is the work function. Here, K.E = 2.0 eV - 1.5 eV = 0.5 eV.
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Modern Physics โ NECO (Nigeria) NECO Physics Practice Questions Online
This page contains 147 practice MCQs for the chapter Modern Physics in NECO (Nigeria) NECO Physics. The questions are organized by difficulty โ 51 easy, 78 medium, 18 hard โ so you can choose the right level for your preparation.
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