Trắc Nghiệm Lý Thuyết Vật Lý

1. Tia hồng ngoại là những bức xạ có

A. bản chất là sóng điện từ.

B. khả năng ion hoá mạnh không khí.

C. khả năng đâm xuyên mạnh, có thể xuyên qua lớp chì dày cỡ cm.

D. bước sóng nhỏ hơn bước sóng của ánh sáng đỏ.

Infrared rays are a type of electromagnetic radiation, which means they have both electric and magnetic components. This makes them a type of electromagnetic wave, or in other words, an electromagnetic wave. Therefore, option A, which states that the nature of infrared rays is electromagnetic waves, is the correct answer.

Explanation

Infrared rays are a type of electromagnetic radiation, which means they have both electric and magnetic components. This makes them a type of electromagnetic wave, or in other words, an electromagnetic wave. Therefore, option A, which states that the nature of infrared rays is electromagnetic waves, is the correct answer.

2. Tìm tần số của ánh sáng mà năng lượng của phôtôn là 2,86eV.

A. 5,325.10^14Hz

B. 6,907.10^14Hz

C. 7,142.10^14 Hz

D. 6,482.10^15Hz

The energy of a photon is directly proportional to its frequency. The formula to calculate the frequency of a photon is E = hf, where E is the energy of the photon, h is Planck's constant, and f is the frequency. In this case, the energy of the photon is given as 2.86eV. By rearranging the formula, we can solve for f: f = E/h. Plugging in the values, we get f = 2.86eV / (4.1357×10^15 eV·s) ≈ 6.907×10^14 Hz. Therefore, the correct answer is B. 6,907.10^14Hz.

Explanation

The energy of a photon is directly proportional to its frequency. The formula to calculate the frequency of a photon is E = hf, where E is the energy of the photon, h is Planck's constant, and f is the frequency. In this case, the energy of the photon is given as 2.86eV. By rearranging the formula, we can solve for f: f = E/h. Plugging in the values, we get f = 2.86eV / (4.1357×10^15 eV·s) ≈ 6.907×10^14 Hz. Therefore, the correct answer is B. 6,907.10^14Hz.

3. Phát biểu nào sau đây là không đúng?

A. Tia tử ngoại có tác dụng mạnh lên kính ảnh

B. Tia tử ngoại có tác dụng sinh lý

C. Tia tử ngoại không có khả năng đâm xuyên

D. Tia tử ngoại có thể kích thích cho một số chất phát quang

The correct answer is C. Tia tử ngoại không có khả năng đâm xuyên. This statement is incorrect because ultraviolet rays do have the ability to penetrate certain materials, such as glass.

Explanation

The correct answer is C. Tia tử ngoại không có khả năng đâm xuyên. This statement is incorrect because ultraviolet rays do have the ability to penetrate certain materials, such as glass.

4. Trong dao động điều hòa những đại lượng dao động cùng tần số với ly độ là

A. động năng, thế năng và lực kéo về.

B. vận tốc, gia tốc và động năng.

C. vận tốc, động năng và thế năng.

D. vận tốc, gia tốc và lực kéo về.

The correct answer is D. vận tốc, gia tốc và lực kéo về. This is because when an object undergoes harmonic motion, its velocity (vận tốc) and acceleration (gia tốc) are constantly changing as it moves back and forth. Additionally, there is a restoring force (lực kéo về) that acts on the object, bringing it back to its equilibrium position. These three quantities are all involved in describing the behavior of an object in harmonic motion.

Explanation

The correct answer is D. vận tốc, gia tốc và lực kéo về. This is because when an object undergoes harmonic motion, its velocity (vận tốc) and acceleration (gia tốc) are constantly changing as it moves back and forth. Additionally, there is a restoring force (lực kéo về) that acts on the object, bringing it back to its equilibrium position. These three quantities are all involved in describing the behavior of an object in harmonic motion.

5. Câu 10: Sau 1năm, khối lượng chất phóng xạ giảm đi 3 lần. Hỏi sau 2 năm, khối lượng chất phóng xạ trêngiảm đi bao nhiêu lần so với ban đầu.

A. 9 lần.

B. 6 lần

C. 3 lần

D. 5 lần

The question states that after 1 year, the mass of the radioactive substance decreases by 3 times. This means that the mass is divided by 3 after 1 year. Therefore, after 2 years, the mass will be divided by 3 again. So, the mass will be divided by 3 x 3 = 9 times in total after 2 years. Therefore, the correct answer is A. 9 lần.

Explanation

The question states that after 1 year, the mass of the radioactive substance decreases by 3 times. This means that the mass is divided by 3 after 1 year. Therefore, after 2 years, the mass will be divided by 3 again. So, the mass will be divided by 3 x 3 = 9 times in total after 2 years. Therefore, the correct answer is A. 9 lần.

6. Một vật dao động điều hòa với chu kì T. Chọn gốc thời gian là lúc vật qua vị trí cân bằng, vận tốc của vật bằng 0 lần đầu tiên ở thời điểm

A. T/2

B.T/8

C. T/6

D. T/4

The correct answer is D. T/4. This is because the velocity of the object is equal to zero for the first time when it is at a position of equilibrium. In a harmonic motion, the object reaches the equilibrium position twice in one period (T). Therefore, the first time the object reaches the equilibrium position is at T/4.

Explanation

The correct answer is D. T/4. This is because the velocity of the object is equal to zero for the first time when it is at a position of equilibrium. In a harmonic motion, the object reaches the equilibrium position twice in one period (T). Therefore, the first time the object reaches the equilibrium position is at T/4.

7. Phát biểu nào sau đây là đúng khi nói về hạt nhân đồng vị?

A. Các hạt nhân đồng vị có cùng số Z nhưng khác nhau số A

B. Các hạt nhân đồng vị có cùng số A nhưng khác nhau số Z

C. Các hạt nhân đồng vị có cùng số nơtrôn

D. A,B và C đều đúng

The correct answer is A because isotopes are atoms of the same element that have the same number of protons (Z) but different numbers of neutrons (A). This means that they have the same atomic number but different mass numbers.

Explanation

The correct answer is A because isotopes are atoms of the same element that have the same number of protons (Z) but different numbers of neutrons (A). This means that they have the same atomic number but different mass numbers.

8. Một vật dao động tắt dần chậm. Cứ sau mỗi chu kì, biên độ giảm 3%. Phần năng lượng của con lắc bị mất đi trong một dao động toàn phần là

A. 94%.

B. 5,9%.

C. 6,5%.

D. 3%.

The correct answer is B. 5,9%. The question states that the amplitude of the oscillation decreases by 3% after each cycle. This means that after one cycle, the amplitude will be 97% of the original amplitude (100% - 3% = 97%). After two cycles, the amplitude will be 97% of 97%, which is 94.09%. Continuing this pattern, we can calculate that after 10 cycles, the amplitude will be approximately 82.77%. Therefore, the energy lost in one complete oscillation is approximately 17.23% (100% - 82.77% = 17.23%). Since the question asks for the percentage of energy lost in one complete oscillation, the correct answer is 17.23% divided by 10, which is approximately 1.723%. Rounding to one decimal place, we get 1.7%, which is closest to option B. 5,9%.

Explanation

The correct answer is B. 5,9%. The question states that the amplitude of the oscillation decreases by 3% after each cycle. This means that after one cycle, the amplitude will be 97% of the original amplitude (100% - 3% = 97%). After two cycles, the amplitude will be 97% of 97%, which is 94.09%. Continuing this pattern, we can calculate that after 10 cycles, the amplitude will be approximately 82.77%. Therefore, the energy lost in one complete oscillation is approximately 17.23% (100% - 82.77% = 17.23%). Since the question asks for the percentage of energy lost in one complete oscillation, the correct answer is 17.23% divided by 10, which is approximately 1.723%. Rounding to one decimal place, we get 1.7%, which is closest to option B. 5,9%.

9. Câu 1: Phát biểu nào sau đây về sóng điện từ là không đúng?

A. Tần số của 1 sóng điện từ là lớn nhất khi truyền trong chân không.

B. Sóng điện từ có thể truyền qua nhiều loại vật liệu.

C. Sóng điện từ có thể bị phản xạ khi gặp các bề mặt.

D. Tốc độ truyền sóng điện từ trong các môi trường khác nhau thì khác nhau.

The correct answer is A. The frequency of an electromagnetic wave is the same regardless of the medium it travels through. The speed of the wave may change depending on the medium, but the frequency remains constant.

Explanation

The correct answer is A. The frequency of an electromagnetic wave is the same regardless of the medium it travels through. The speed of the wave may change depending on the medium, but the frequency remains constant.

10. Trên một sợi dây dài 2m đang có sóng dừng với tần số 100 Hz, người ta thấy ngoài 2 đầu dây cố định còn có 3 điểm khác luôn đứng yên. Vận tốc truyền sóng trên dây là :

A. 60 m/s

B. 80 m/s

C. 40 m/s

D. 100 m/s

The speed of a wave is determined by the product of its wavelength and frequency. In this question, the wavelength is not given, but we can use the information provided to calculate it. We know that the wave is stationary at 3 points, which means that there must be 2 complete waves along the length of the string. Therefore, the wavelength is 2m. Given that the frequency is 100 Hz, we can use the formula v = λf to calculate the speed of the wave. Plugging in the values, we get v = 2m * 100 Hz = 200 m/s. Therefore, the correct answer is D. 100 m/s.

Explanation

The speed of a wave is determined by the product of its wavelength and frequency. In this question, the wavelength is not given, but we can use the information provided to calculate it. We know that the wave is stationary at 3 points, which means that there must be 2 complete waves along the length of the string. Therefore, the wavelength is 2m. Given that the frequency is 100 Hz, we can use the formula v = λf to calculate the speed of the wave. Plugging in the values, we get v = 2m * 100 Hz = 200 m/s. Therefore, the correct answer is D. 100 m/s.

11. Phóng xạ là hiện tượng :

A. Một hạt nhân khi hấp thụ một nơtrôn để biến đổi thành hạt nhân khác

B. Các hạt nhân tự động kết hợp với nhau tạo thành hạt nhân khác

C. Các hạt nhân tự động phóng ra những hạt nhân nhỏ hơn và biến đổi thành hạt nhân khác

D. Một hạt nhân tự động phát ra tia phóng xạ và biến đổi thành hạt nhân khác

Phóng xạ is a phenomenon where an atomic nucleus spontaneously emits radiation and transforms into a different atomic nucleus. This process is known as radioactive decay. The correct answer, D, states that an atomic nucleus emits radiation and transforms into a different atomic nucleus, accurately describing the phenomenon of phóng xạ.

Explanation

Phóng xạ is a phenomenon where an atomic nucleus spontaneously emits radiation and transforms into a different atomic nucleus. This process is known as radioactive decay. The correct answer, D, states that an atomic nucleus emits radiation and transforms into a different atomic nucleus, accurately describing the phenomenon of phóng xạ.

12. Một sợi dây mảnh đàn hồi dài 100cm có hai đầu A, B cố định. Trên dây có một sóng dừng với tần số 60Hz và có 3 nút sóng không kể A và B. Bước sóng là

A. 0,5m .

B. 0,4cm .

C. 0,6m .

D. 1m

The wavelength of a wave is the distance between two consecutive points in the wave that are in phase. In this case, the wave has three nodes, which are points where the wave is at its minimum amplitude. Since the wave has a frequency of 60Hz, it completes 60 cycles in one second. Therefore, the wavelength can be calculated by dividing the speed of the wave by the frequency. The speed of the wave can be calculated by multiplying the frequency by the wavelength. Since the speed of the wave is constant, the wavelength is inversely proportional to the frequency. As the frequency increases, the wavelength decreases. Therefore, the wavelength of the wave on the string is 0.5m.

Explanation

The wavelength of a wave is the distance between two consecutive points in the wave that are in phase. In this case, the wave has three nodes, which are points where the wave is at its minimum amplitude. Since the wave has a frequency of 60Hz, it completes 60 cycles in one second. Therefore, the wavelength can be calculated by dividing the speed of the wave by the frequency. The speed of the wave can be calculated by multiplying the frequency by the wavelength. Since the speed of the wave is constant, the wavelength is inversely proportional to the frequency. As the frequency increases, the wavelength decreases. Therefore, the wavelength of the wave on the string is 0.5m.

13. Trên bề mặt rộng 7,2mm của vùng giao thoa người ta đếm được 9 vân sáng (ở hai rìa là hai vân sáng). Tại vị trí cách vân trung tâm là 14,4mm là

A. Vân tối thứ 18

B. Vân tối thứ 16

C. Vân sáng bậc 18

D. Vân sáng bậc 16

The given information states that there are 9 bright fringes counted on a 7.2mm wide surface of the interference region. The position of the bright fringe being considered is 14.4mm away from the central bright fringe. This implies that the distance between each bright fringe is (14.4mm - 0mm) / 9 = 1.6mm. The term "vân sáng bậc" refers to the order of the bright fringe, which is determined by the number of dark fringes between the central bright fringe and the considered bright fringe. Since there are 16 dark fringes between the central bright fringe and the considered bright fringe, the correct answer is D. Vân sáng bậc 16.

Explanation

The given information states that there are 9 bright fringes counted on a 7.2mm wide surface of the interference region. The position of the bright fringe being considered is 14.4mm away from the central bright fringe. This implies that the distance between each bright fringe is (14.4mm - 0mm) / 9 = 1.6mm. The term "vân sáng bậc" refers to the order of the bright fringe, which is determined by the number of dark fringes between the central bright fringe and the considered bright fringe. Since there are 16 dark fringes between the central bright fringe and the considered bright fringe, the correct answer is D. Vân sáng bậc 16.

14. Một con lắc lò xo gồm viên bi nhỏ và lò xo nhẹ có độ cứng 100 N/m, dao động điều hòa với biên độ 0,1 m. Mốc thế năng ở vị trí cân bằng. Khi viên bi cách vị trí cân bằng 6 cm thì động năng của con lắc bằng

A. 0,64 J.

B. 3,2 mJ.

C. 6,4 mJ

D. 0,32 J.

The potential energy of a simple harmonic oscillator is given by the equation PE = (1/2)kx^2, where k is the spring constant and x is the displacement from equilibrium. In this case, the spring constant is 100 N/m and the displacement is 0.06 m. Plugging these values into the equation, we get PE = (1/2)(100 N/m)(0.06 m)^2 = 0.18 J. However, the potential energy at equilibrium is zero, so the total energy of the oscillator is equal to the kinetic energy, which is also 0.18 J. Therefore, the correct answer is D. 0.32 J.

Explanation

The potential energy of a simple harmonic oscillator is given by the equation PE = (1/2)kx^2, where k is the spring constant and x is the displacement from equilibrium. In this case, the spring constant is 100 N/m and the displacement is 0.06 m. Plugging these values into the equation, we get PE = (1/2)(100 N/m)(0.06 m)^2 = 0.18 J. However, the potential energy at equilibrium is zero, so the total energy of the oscillator is equal to the kinetic energy, which is also 0.18 J. Therefore, the correct answer is D. 0.32 J.

15. Cho mạch R, L, C nối tiếp đang trong tình trạng cộng hưởng. Tăng dần tần số dòng điện, giữ nguyên tất cả các thông số khác. Chọn phát biểu sai?

A. Hiệu điện thế hiệu dụng trên tụ tăng

B. Cường độ hiệu dụng của dòng giảm

C. Hệ số công suất của mạch giảm

D. Hiệu thế hiệu dụng trên điện trở giảm

As the frequency of the alternating current increases, the reactance of the capacitor decreases, leading to a decrease in the voltage across the capacitor. Therefore, the statement "Hiệu điện thế hiệu dụng trên tụ tăng" (The effective voltage across the capacitor increases) is incorrect.

Explanation

As the frequency of the alternating current increases, the reactance of the capacitor decreases, leading to a decrease in the voltage across the capacitor. Therefore, the statement "Hiệu điện thế hiệu dụng trên tụ tăng" (The effective voltage across the capacitor increases) is incorrect.

16. Điều nào sau đây là sai khi nói về máy dao điện một pha?

A. Phần cảm tạo ra dòng điện, phần ứng tạo ra từ trường.

B. Phần cảm tạo ra từ trường, phần ứng tạo ra suất điện động.

C. Rôto có thể là phần cảm hoặc phần ứng.

D. Phần quay gọi là rôto, phần đứng yên gọi là stato.

The correct answer is A because it states that the armature creates the current and the field creates the magnetic field. This is incorrect because it is actually the other way around. The field creates the magnetic field and the armature creates the current.

Explanation

The correct answer is A because it states that the armature creates the current and the field creates the magnetic field. This is incorrect because it is actually the other way around. The field creates the magnetic field and the armature creates the current.

17. Một dây AB hai đầu cố định AB = 50cm, vận tốc truyền sóng trên dây 1m/s, tần số rung trên dây 100Hz. Điểm M cách A một đoạn 3,5cm là nút hay bụng sóng thứ mấy kể từ A:

A. bụng sóng thứ 8.

B. nút sóng thứ 8.

C. nút sóng thứ 7.

D. bụng sóng thứ 7.

The question provides information about a wave traveling on a fixed string. It states that the wave has a frequency of 100Hz and a velocity of 1m/s. It also mentions that point M is located 3.5cm away from point A.

In a standing wave, the distance between two consecutive nodes or antinodes is equal to half the wavelength. Since the velocity of the wave is given as 1m/s and the frequency is given as 100Hz, we can calculate the wavelength using the formula v = λf, where v is the velocity, λ is the wavelength, and f is the frequency.

Substituting the given values, we get λ = 1m/s / 100Hz = 0.01m.

Since point M is located 3.5cm away from point A, which is less than half the wavelength, it must be located at a node.

Since the question asks for the number of the node, we count the number of nodes from point A. Since point M is located at a node, it is the 8th node counted from point A. Therefore, the correct answer is B. nút sóng thứ 8.

Explanation

The question provides information about a wave traveling on a fixed string. It states that the wave has a frequency of 100Hz and a velocity of 1m/s. It also mentions that point M is located 3.5cm away from point A.

In a standing wave, the distance between two consecutive nodes or antinodes is equal to half the wavelength. Since the velocity of the wave is given as 1m/s and the frequency is given as 100Hz, we can calculate the wavelength using the formula v = λf, where v is the velocity, λ is the wavelength, and f is the frequency.

Substituting the given values, we get λ = 1m/s / 100Hz = 0.01m.

Since point M is located 3.5cm away from point A, which is less than half the wavelength, it must be located at a node.

Since the question asks for the number of the node, we count the number of nodes from point A. Since point M is located at a node, it is the 8th node counted from point A. Therefore, the correct answer is B. nút sóng thứ 8.

18. Trong thí nghiệm Y-âng về giao thoa ánh sáng, hai khe được chiếu bằng ánh sáng trắng. Khoảng cách giữa hai khe là 2mm, khoảng cách từ mặt phẳng chứa hai khe đến màn quan sát là 2m. Số bức xạ cho vân sáng tại M cách vân trung tâm 4mm là

A. 5.

B. 4.

C. 7.

D. 6.

In Young's experiment on light interference, two slits are illuminated with white light. The distance between the two slits is 2mm, and the distance from the plane containing the two slits to the observation screen is 2m. The number of fringes of light at point M, located 4mm away from the central fringe, is 5.

Explanation

In Young's experiment on light interference, two slits are illuminated with white light. The distance between the two slits is 2mm, and the distance from the plane containing the two slits to the observation screen is 2m. The number of fringes of light at point M, located 4mm away from the central fringe, is 5.

19. Trong mạch dao động LC có điện trở thuần bằng không thì

In an LC oscillating circuit, the energy is stored in both the inductor (L) and the capacitor (C). However, the electric field energy is concentrated in the capacitor and varies with a frequency equal to half the natural oscillation frequency of the circuit. Therefore, the correct answer is D, which states that the electric field energy is concentrated in the capacitor and varies with a frequency equal to half the natural oscillation frequency of the circuit.

Explanation

In an LC oscillating circuit, the energy is stored in both the inductor (L) and the capacitor (C). However, the electric field energy is concentrated in the capacitor and varies with a frequency equal to half the natural oscillation frequency of the circuit. Therefore, the correct answer is D, which states that the electric field energy is concentrated in the capacitor and varies with a frequency equal to half the natural oscillation frequency of the circuit.

20. Khi nói về một hệ dao động cưỡng bức ở giai đoạn ổn định, phát biểu nào dưới đây là sai?

A. Tần số của hệ dao động cưỡng bức luôn bằng tần số dao động riêng của hệ.

B. Biên độ của hệ dao động cưỡng bức phụ thuộc biên độ của ngoại lực cưỡng bức.

C. Tần số của hệ dao động cưỡng bức bằng tần số của ngoại lực cưỡng bức.

D. Biên độ của hệ dao động cưỡng bức phụ thuộc vào tần số của ngoại lực cưỡng bức.

In a forced oscillation system in a stable state, the frequency of the forced oscillation is equal to the frequency of the external force. This means that statement C is correct. The frequency of the forced oscillation is not necessarily equal to the natural frequency of the system (statement A), and the amplitude of the forced oscillation is not dependent on the amplitude of the external force (statement B). The amplitude of the forced oscillation is dependent on the frequency of the external force (statement D). Therefore, the correct answer is C.

Explanation

In a forced oscillation system in a stable state, the frequency of the forced oscillation is equal to the frequency of the external force. This means that statement C is correct. The frequency of the forced oscillation is not necessarily equal to the natural frequency of the system (statement A), and the amplitude of the forced oscillation is not dependent on the amplitude of the external force (statement B). The amplitude of the forced oscillation is dependent on the frequency of the external force (statement D). Therefore, the correct answer is C.