Dao động và Sóng điện từ Practice Questions
THPT (Vietnam) · THPT Vật lý · 147 free MCQs with instant results and detailed explanations.
147
Total
47
Easy
77
Medium
23
Hard
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Sample Questions from Dao động và Sóng điện từ
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Q1
Easy
Which of the following best describes electromagnetic waves?
A.
They require a medium to travel through.
B.
They travel at the speed of light in a vacuum.
C.
They are only visible to the human eye.
D.
They cannot travel through empty space.
Show Answer & Explanation
Correct Answer: B
Electromagnetic waves can travel through a vacuum and propagate at the speed of light, approximately 3 x 10^8 m/s, making option B the correct statement.
Q2
Easy
What happens to the wavelength of a wave if its frequency is doubled while the wave speed remains constant?
A.
Wavelength is doubled.
B.
Wavelength is halved.
C.
Wavelength remains the same.
D.
Wavelength decreases by a quarter.
Show Answer & Explanation
Correct Answer: B
According to the wave equation (v = f × λ), if the frequency (f) is doubled and speed (v) is constant, the wavelength (λ) must be halved to maintain the equation's balance.
Q3
Easy
What is the frequency of a wave if its period is 0.05 seconds?
A.
20 Hz
B.
50 Hz
C.
10 Hz
D.
25 Hz
Show Answer & Explanation
Correct Answer: A
Frequency is the reciprocal of the period. Therefore, frequency (f) = 1/period. Here, f = 1/0.05 = 20 Hz.
Q4
Medium
A simple harmonic oscillator has a mass of 2 kg and a spring constant of 100 N/m. What is the maximum speed of the oscillator when it reaches the equilibrium position if the amplitude of oscillation is 0.5 m?
A.
5 m/s
B.
10 m/s
C.
2.5 m/s
D.
1 m/s
Show Answer & Explanation
Correct Answer: A
The maximum speed (v_max) in a harmonic oscillator is given by v_max = A * ω, where ω = √(k/m). Here, A = 0.5m, k = 100 N/m, and m = 2kg, yielding v_max = 0.5 * √(100/2) = 5 m/s.
Q5
Medium
Which of the following statements about electromagnetic waves is true?
A.
They require a medium to propagate.
B.
They travel at the speed of sound in air.
C.
They consist of oscillating electric and magnetic fields.
D.
They can only travel in a vacuum.
Show Answer & Explanation
Correct Answer: C
Electromagnetic waves are characterized by the oscillation of electric and magnetic fields perpendicular to each other and to the direction of wave propagation. They do not require a medium, which makes option C correct.
Q6
Medium
A wave travels along a string and is described by the equation y(x,t) = 0.1 sin(2π(0.5x - 2t)). What is the wavelength of the wave?
A.
2 m
B.
1 m
C.
0.5 m
D.
4 m
Show Answer & Explanation
Correct Answer: B
The general form of a wave equation is y(x,t) = A sin(kx - ωt). The wave number k = 2π/λ, and here k = 2π * 0.5, which gives λ = 1 m.
Q7
Medium
Two waves traveling in the same medium interfere with each other. If the displacement of the first wave is given by y1 = A sin(kx - ωt) and the second is y2 = A sin(kx + ωt), what type of interference occurs?
A.
Constructive interference
B.
Destructive interference
C.
Standing wave formation
D.
No interference
Show Answer & Explanation
Correct Answer: C
The two waves have the same amplitude and frequency but travel in opposite directions. When they interfere, they create a standing wave pattern due to constructive interference at certain points and destructive interference at others.
Q8
Hard
A capacitor is charged to a voltage of 12V and then disconnected from the battery. If the capacitance of the capacitor is 6μF, what is the energy stored in the capacitor?
A.
0.432 mJ
B.
0.864 mJ
C.
0.576 mJ
D.
1.024 mJ
Show Answer & Explanation
Correct Answer: B
The energy (U) stored in a capacitor can be calculated using the formula U = 0.5 * C * V^2. Here, C = 6μF (or 6 x 10^-6 F) and V = 12V. Thus, U = 0.5 * 6 x 10^-6 * (12)^2 = 0.864 mJ.
Q9
Hard
A wave traveling in a medium has a frequency of 500 Hz and a wavelength of 2 m. What is the speed of the wave?
A.
1000 m/s
B.
250 m/s
C.
2000 m/s
D.
750 m/s
Show Answer & Explanation
Correct Answer: A
The speed of a wave can be calculated using the formula: speed = frequency × wavelength. Here, speed = 500 Hz × 2 m = 1000 m/s.
Q10
Hard
An electromagnetic wave in a vacuum has an electric field amplitude of 3 V/m. What is the corresponding magnetic field amplitude?
A.
1 μT
B.
10 μT
C.
0.1 μT
D.
2 μT
Show Answer & Explanation
Correct Answer: B
The ratio of the electric field (E) to the magnetic field (B) in an electromagnetic wave is given by E/B = c, where c is the speed of light (approx. 3 x 10^8 m/s). Thus, B = E/c. Substituting E = 3 V/m, we find B = 3 V/m / (3 x 10^8 m/s) = 1 x 10^-8 T = 10 μT.
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Dao động và Sóng điện từ — THPT (Vietnam) THPT Vật lý Practice Questions Online
This page contains 147 practice MCQs for the chapter Dao động và Sóng điện từ in THPT (Vietnam) THPT Vật lý. The questions are organized by difficulty — 47 easy, 77 medium, 23 hard — so you can choose the right level for your preparation.
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