Chiếu vào catôt của một tế bào quang điện một chùm sáng có tần số và cường độ xác định. Sự phụ thuộc của cường độ dòng điện vào hiệu điện thế đặt vào hai đầu tế bào quang điện được biểu diễn bằng đồ thị hình bên. Nếu giữ nguyên tần số ánh sáng chiếu vào tế bào quang điện nhưng tăng cường độ chùm sáng thì đồ thị nào sau đây biểu diễn sự phụ thuộc của cường độ dòng điện vào hiệu điện thế hai đầu tế bào quang điện?

Động năng ban đầu của các electron quang điện sẽ có giá trị cực đại khi:

Dung dịch flurorêxin hấp thụ ánh sáng có bước sóng λ = 0,45 (μm) và phát ra ánh sáng có bước sóng λ' = 0,50 (μm). Hiệu suất của sự phát quang của dung dịch flurorêxin là 75% thì số phần trăm phôtôn bị hấp thụ đã dẫn đến sự phát quang của phân tử flurorêxin là:

Chiếu một bức xạ có bước sóng 0,18 (μm) vào catốt của một tế bào quang điện có giới hạn quang điện là 0,3 (μm). Để cho không có electron nào đến được anốt thì hiệu điện thế U_AK phải thoả mãn điều kiện nào? Cho điện tích của electron e = -1,6. 10⁻¹⁶ (C), hằng số Flăng h = 6,625. 10⁻³⁴ (Js), c = 3. 10⁸ (m/s).

Chọn phát biểu đúng. Khi cường độ chùm tia sáng mà không thay đổi bước sóng của nó thì:

Cho bước sóng của hai vạch quang phổ trong dãy Banmer của quang phổ nguyên tử hidro là: λ_α = 0,6563μm, λ_r = 0,434μm. Năng lượng của photon ánh sáng do nguyên tử hidro phát ra khi electron chuyển từ quỹ đạo O về quỹ đạo M là:

Khi nói về thuyết phôtôn ánh sáng (thuyết lượng tử ánh sáng), phát biểu nào sau đây là sai?

Hiệu ứng quang điện là một hiện tượng phát xạ điện tử gây ra bởi:

Nguyên tắc hoạt động của quang điện trở dựa vào:

 Pin quang điện có khả năng biến đổi:

Hệ số hấp thụ của môi trường phụ thuộc vào:

Ánh sáng huỳnh quang là ánh sáng phát quang:

Trong điều kiện bước sóng kích thích thoả mãn λ ≤ λ₀ và với một hiệu điện thế U nhất định giữa anôt và catốt, cường độ dòng quang điện:

Khi một nguyên tử phát ra phôtôn thì có nghĩa là một trong các êlectron của nó:

Một kim loại có bước sóng giới hạn là λ. Ánh sáng kích thích có bước sóng là  . Động năng cực đại ban đầu của quang electron là:

Chọn câu trả lời đúng. Biết mức năng lượng ứng với quỹ đạo dừng n trong nguyên tử hiđrô: E_n = − (eV); n = 1,2,3.... Khi hiđrô ở trạng thái cơ bản được kích thích chuyển lên trạng thái có bán kính quỹ đạo tăng lên 9 lần. Khi chuyển dời về mức cơ bản thì phát ra bước sóng của bức xạ có năng lượng lớn nhất là:

Khi chiếu một chùm sáng trắng song song trước khi vào catôt của một tế bào quang điện, người ta đặt lần lượt các tấm kính lọc sắc để lấy ra các thành phần đơn sắc khác nhau và thấy khi dùng kính màu lam thì hiện tượng quang điện bắt đầu xảy ra. Nếu cất kính lọc sắc thì cường độ dòng quang điện

Trong laze rubi có sự biến đổi của dạng năng lượng nào dưới đây thành quang năng?

Hiện tượng quang điện là quá trình dựa trên:

Chiếu vào catôt của một tế bào quang điện một chùm sáng có tần số và cường độ xác định. Sự phụ thuộc của cường độ dòng điện vào hiệu điện thế đặt vào hai đầu tế bào quang điện được biểu diễn bằng đồ thị hình bên. Nếu giữ nguyên tần số ánh sáng chiếu vào tế bào quang điện nhưng tăng cường độ chùm sáng thì đồ thị nào sau đây biểu diễn sự phụ thuộc của cường độ dòng điện vào hiệu điện thế hai đầu tế bào quang điện?

Năng lượng ion hóa nguyên tử hidro là A_i = 13,6eV. Bước sóng của vạch quang phổ ngắn nhất trong dãy Laiman bằng:

Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct word or phrase that best fits each of the numbered blanks from 27 to 38:

On a winter afternoon, a dozen male Northern fur seals are on an island off south - western Alaska. To look at them, fighting for territory on the rocks, it’s hard to imagine that they are at the (27)____________of a baffling scientific mystery: why is this species beginning to disappear? These seals - which can weigh up to 270 kilograms - have an important and symbolic (28)_________in Alaska’s history. Their soft and luxurious fur, the coveted prize during the huge commercial sea harvests that were legal here in the Bering Sea through the early 20th century, was once so valuable it (29)_________Alaska’s economy. Starting in the 1950s, for reasons that are (30)_______because the harvests by then tended to be fairly small, the seal population began a slow decline. But lately it has been falling drastically, declining at an alarming (31)________of 6 per cent a year since 1998. From a (32)_________ of more than 2 million in Alaska in 1948, their numbers have fallen to about 1 million. So (33)________, no one has been able to establish a precise cause for this, although theories (34)___________. The seal's food supply may be (35)________, or another species may be (36)________on the seals - perhaps killer whales, which no longer have as many great whales to eat because of harvesting of those mammals. Some people have suggested that the decline can be (37)______to entanglement in fishing nets, but scientists say they doubt that this alone could (38)_________the recent population decline.

Question 35:

Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct word or phrase that best fits each of the numbered blanks from 27 to 38:

On a winter afternoon, a dozen male Northern fur seals are on an island off south - western Alaska. To look at them, fighting for territory on the rocks, it’s hard to imagine that they are at the (27)____________of a baffling scientific mystery: why is this species beginning to disappear? These seals - which can weigh up to 270 kilograms - have an important and symbolic (28)_________in Alaska’s history. Their soft and luxurious fur, the coveted prize during the huge commercial sea harvests that were legal here in the Bering Sea through the early 20th century, was once so valuable it (29)_________Alaska’s economy. Starting in the 1950s, for reasons that are (30)_______because the harvests by then tended to be fairly small, the seal population began a slow decline. But lately it has been falling drastically, declining at an alarming (31)________of 6 per cent a year since 1998. From a (32)_________ of more than 2 million in Alaska in 1948, their numbers have fallen to about 1 million. So (33)________, no one has been able to establish a precise cause for this, although theories (34)___________. The seal's food supply may be (35)________, or another species may be (36)________on the seals - perhaps killer whales, which no longer have as many great whales to eat because of harvesting of those mammals. Some people have suggested that the decline can be (37)______to entanglement in fishing nets, but scientists say they doubt that this alone could (38)_________the recent population decline.

Question 34:

Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct word or phrase that best fits each of the numbered blanks from 27 to 38:

On a winter afternoon, a dozen male Northern fur seals are on an island off south - western Alaska. To look at them, fighting for territory on the rocks, it’s hard to imagine that they are at the (27)____________of a baffling scientific mystery: why is this species beginning to disappear? These seals - which can weigh up to 270 kilograms - have an important and symbolic (28)_________in Alaska’s history. Their soft and luxurious fur, the coveted prize during the huge commercial sea harvests that were legal here in the Bering Sea through the early 20th century, was once so valuable it (29)_________Alaska’s economy. Starting in the 1950s, for reasons that are (30)_______because the harvests by then tended to be fairly small, the seal population began a slow decline. But lately it has been falling drastically, declining at an alarming (31)________of 6 per cent a year since 1998. From a (32)_________ of more than 2 million in Alaska in 1948, their numbers have fallen to about 1 million. So (33)________, no one has been able to establish a precise cause for this, although theories (34)___________. The seal's food supply may be (35)________, or another species may be (36)________on the seals - perhaps killer whales, which no longer have as many great whales to eat because of harvesting of those mammals. Some people have suggested that the decline can be (37)______to entanglement in fishing nets, but scientists say they doubt that this alone could (38)_________the recent population decline.

Question 31:

Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct word or phrase that best fits each of the numbered blanks from 27 to 38:

On a winter afternoon, a dozen male Northern fur seals are on an island off south - western Alaska. To look at them, fighting for territory on the rocks, it’s hard to imagine that they are at the (27)____________of a baffling scientific mystery: why is this species beginning to disappear? These seals - which can weigh up to 270 kilograms - have an important and symbolic (28)_________in Alaska’s history. Their soft and luxurious fur, the coveted prize during the huge commercial sea harvests that were legal here in the Bering Sea through the early 20th century, was once so valuable it (29)_________Alaska’s economy. Starting in the 1950s, for reasons that are (30)_______because the harvests by then tended to be fairly small, the seal population began a slow decline. But lately it has been falling drastically, declining at an alarming (31)________of 6 per cent a year since 1998. From a (32)_________ of more than 2 million in Alaska in 1948, their numbers have fallen to about 1 million. So (33)________, no one has been able to establish a precise cause for this, although theories (34)___________. The seal's food supply may be (35)________, or another species may be (36)________on the seals - perhaps killer whales, which no longer have as many great whales to eat because of harvesting of those mammals. Some people have suggested that the decline can be (37)______to entanglement in fishing nets, but scientists say they doubt that this alone could (38)_________the recent population decline.

Question 30:

Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct word or phrase that best fits each of the numbered blanks from 27 to 38:

On a winter afternoon, a dozen male Northern fur seals are on an island off south - western Alaska. To look at them, fighting for territory on the rocks, it’s hard to imagine that they are at the (27)____________of a baffling scientific mystery: why is this species beginning to disappear? These seals - which can weigh up to 270 kilograms - have an important and symbolic (28)_________in Alaska’s history. Their soft and luxurious fur, the coveted prize during the huge commercial sea harvests that were legal here in the Bering Sea through the early 20th century, was once so valuable it (29)_________Alaska’s economy. Starting in the 1950s, for reasons that are (30)_______because the harvests by then tended to be fairly small, the seal population began a slow decline. But lately it has been falling drastically, declining at an alarming (31)________of 6 per cent a year since 1998. From a (32)_________ of more than 2 million in Alaska in 1948, their numbers have fallen to about 1 million. So (33)________, no one has been able to establish a precise cause for this, although theories (34)___________. The seal's food supply may be (35)________, or another species may be (36)________on the seals - perhaps killer whales, which no longer have as many great whales to eat because of harvesting of those mammals. Some people have suggested that the decline can be (37)______to entanglement in fishing nets, but scientists say they doubt that this alone could (38)_________the recent population decline.

Question 33:

Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct word or phrase that best fits each of the numbered blanks from 27 to 38:

On a winter afternoon, a dozen male Northern fur seals are on an island off south - western Alaska. To look at them, fighting for territory on the rocks, it’s hard to imagine that they are at the (27)____________of a baffling scientific mystery: why is this species beginning to disappear? These seals - which can weigh up to 270 kilograms - have an important and symbolic (28)_________in Alaska’s history. Their soft and luxurious fur, the coveted prize during the huge commercial sea harvests that were legal here in the Bering Sea through the early 20th century, was once so valuable it (29)_________Alaska’s economy. Starting in the 1950s, for reasons that are (30)_______because the harvests by then tended to be fairly small, the seal population began a slow decline. But lately it has been falling drastically, declining at an alarming (31)________of 6 per cent a year since 1998. From a (32)_________ of more than 2 million in Alaska in 1948, their numbers have fallen to about 1 million. So (33)________, no one has been able to establish a precise cause for this, although theories (34)___________. The seal's food supply may be (35)________, or another species may be (36)________on the seals - perhaps killer whales, which no longer have as many great whales to eat because of harvesting of those mammals. Some people have suggested that the decline can be (37)______to entanglement in fishing nets, but scientists say they doubt that this alone could (38)_________the recent population decline.

Question 32:

Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct word or phrase that best fits each of the numbered blanks from 27 to 38:

On a winter afternoon, a dozen male Northern fur seals are on an island off south - western Alaska. To look at them, fighting for territory on the rocks, it’s hard to imagine that they are at the (27)____________of a baffling scientific mystery: why is this species beginning to disappear? These seals - which can weigh up to 270 kilograms - have an important and symbolic (28)_________in Alaska’s history. Their soft and luxurious fur, the coveted prize during the huge commercial sea harvests that were legal here in the Bering Sea through the early 20th century, was once so valuable it (29)_________Alaska’s economy. Starting in the 1950s, for reasons that are (30)_______because the harvests by then tended to be fairly small, the seal population began a slow decline. But lately it has been falling drastically, declining at an alarming (31)________of 6 per cent a year since 1998. From a (32)_________ of more than 2 million in Alaska in 1948, their numbers have fallen to about 1 million. So (33)________, no one has been able to establish a precise cause for this, although theories (34)___________. The seal's food supply may be (35)________, or another species may be (36)________on the seals - perhaps killer whales, which no longer have as many great whales to eat because of harvesting of those mammals. Some people have suggested that the decline can be (37)______to entanglement in fishing nets, but scientists say they doubt that this alone could (38)_________the recent population decline.

Question 27: 

Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct word or phrase that best fits each of the numbered blanks from 27 to 38:

On a winter afternoon, a dozen male Northern fur seals are on an island off south - western Alaska. To look at them, fighting for territory on the rocks, it’s hard to imagine that they are at the (27)____________of a baffling scientific mystery: why is this species beginning to disappear? These seals - which can weigh up to 270 kilograms - have an important and symbolic (28)_________in Alaska’s history. Their soft and luxurious fur, the coveted prize during the huge commercial sea harvests that were legal here in the Bering Sea through the early 20th century, was once so valuable it (29)_________Alaska’s economy. Starting in the 1950s, for reasons that are (30)_______because the harvests by then tended to be fairly small, the seal population began a slow decline. But lately it has been falling drastically, declining at an alarming (31)________of 6 per cent a year since 1998. From a (32)_________ of more than 2 million in Alaska in 1948, their numbers have fallen to about 1 million. So (33)________, no one has been able to establish a precise cause for this, although theories (34)___________. The seal's food supply may be (35)________, or another species may be (36)________on the seals - perhaps killer whales, which no longer have as many great whales to eat because of harvesting of those mammals. Some people have suggested that the decline can be (37)______to entanglement in fishing nets, but scientists say they doubt that this alone could (38)_________the recent population decline.

Question 29:

Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct word or phrase that best fits each of the numbered blanks from 27 to 38:

On a winter afternoon, a dozen male Northern fur seals are on an island off south - western Alaska. To look at them, fighting for territory on the rocks, it’s hard to imagine that they are at the (27)____________of a baffling scientific mystery: why is this species beginning to disappear? These seals - which can weigh up to 270 kilograms - have an important and symbolic (28)_________in Alaska’s history. Their soft and luxurious fur, the coveted prize during the huge commercial sea harvests that were legal here in the Bering Sea through the early 20th century, was once so valuable it (29)_________Alaska’s economy. Starting in the 1950s, for reasons that are (30)_______because the harvests by then tended to be fairly small, the seal population began a slow decline. But lately it has been falling drastically, declining at an alarming (31)________of 6 per cent a year since 1998. From a (32)_________ of more than 2 million in Alaska in 1948, their numbers have fallen to about 1 million. So (33)________, no one has been able to establish a precise cause for this, although theories (34)___________. The seal's food supply may be (35)________, or another species may be (36)________on the seals - perhaps killer whales, which no longer have as many great whales to eat because of harvesting of those mammals. Some people have suggested that the decline can be (37)______to entanglement in fishing nets, but scientists say they doubt that this alone could (38)_________the recent population decline.

Question 28: 

Read the following passage and mark the letter A, B, C, or D to indicate the correct word or phrase that best fits each of the numbered blanks from 24 to 28:

 Personal space is a term that refers (24)_____the distance we like to keep between ourselves and other people. When (25) ______we do not know well gets too close we usually begin to feel uncomfortable. If a business colleague comes closer than 1.2 meters, the most common response is to move (26)______. Some interesting (27)______have been done in libraries. If strangers come too close, many people get up and leave the building; others use different methods such as turning their back on the intruder. Living in cities has made people develop new skills for dealing with situations where they are very close to strangers. Most people on crowded trains try not to look at strangers; they avoid skin contact, and apologize if hands touch by mistake. People use newspapers (28) ______a barrier between themselves and other people, and if they do not have one, they stare into the distance, making sure they are not looking into anyone’s eyes.

Question 24: