Cường độ dòng điện i = 4cos100πt (A) có pha tại thời điểm t là:

Cường độ dòng điện trong một đoạn mạch có biểu thức (A). Cường độ hiệu dụng của dòng điện này là ?

Dòng điện xoay chiều có tần số f = 60Hz. Trong 1s dòng điện đổi chiều:

Đặt điện áp xoay chiều u có tần số góc ω vào hai đầu đoạn mạch mắc nối tiếp gồm điện trở R và tụ điện C thay đổi được. Gọi i là cường độ dòng điện trong mạch, φ là độ lệch pha giữa u và i. Hình bên là đồ thị biểu diễn sự phụ thuộc của φ theo Z_C. Giá trị của R là:  

Đặt vào hai đầu đoạn mạch chỉ có cuộn cảm thuần một điện áp xoay chiều có biểu thức  thì cường độ dòng điện trong mạch là i = I0cos(ωt + φ)A. Giá trị của φ là:

Một vòng dây có diện tích và điện trở , quay đều với tốc độ góc trong một từ trường đều có cảm ứng từ xung quanh một trục nằm trong mặt phẳng vòng dây và vuông góc với các đường sức từ. Nhiệt lượng tỏa ra trong vòng dây khi nó quay được là:                         

Chọn câu sai. Dòng điện xoay chiều có cường độ  (A). Dòng điện này có :        

Hình bên là đồ thị biểu diễn sự phụ thuộc của điện áp xoay chiều u ở hai đầu một đoạn mạch theo thời gian t. Điện áp hiệu dụng ở hai đầu đoạn mạch này bằng:

Điện áp tức thời . Trong thời gian 0,05s kể từ thời điểm ban đầu . Số lần điện áp u =150V:  

Đặt điện áp  vào hai đầu đoạn mạch điện. Tại thời điểm t, điện áp có giá trị và đang giảm. Tại thời điểm , điện áp này có giá trị bằng:

Cường độ dòng điện trong mạch không phân nhánh có dạng i = 2cos100πt (A). Cường độ dòng điện hiệu dụng trong mạch là ?        

Từ thông qua một vòng dây dẫn là  Biểu thức của suất điện động cảm ứng xuất hiện trong vòng dây này là ?  

Một dòng điện xoay chiều có biểu thức cường độ dòng điện (A). Pha của dòng điện ở thời điểm t là:

Cường độ dòng điện tức thời chạy qua một đoạn mạch xoay chiều là I = 2sin(100πt) A. Tại thời điểm t₁ nào đó, dòng điện đang giảm và có cường độ bằng 1 A. Đến thời điểm t = t₁ + 0,005 s, cường độ dòng điện bằng         

dòng điện woay chiều chạy qua một đoạn mạch có biểu thức cương độ dòng điện ,với I₀ > 0. Tính từ lúc t=0 (s),điiện lượng chuyển qua tiết diện thẳng của dây dẫn của đoạn mạch đó trong thời gian bằng nũa chu kỳ của dong điện là:           

Khung dây kim loại phẳng có diện tích S = 120cm², có N = 1000 vòng dây, quay đều với tốc độ 3000 vòng/phút quanh trục vuông góc với đường sức của một từ trường đều B = 0,01 (T). Suất  điện động  cảm ứng xuất hiện trong khung dây có giá trị hiệu dụng bằng: 

Chọn phát biểu đúng:

Điện áp ở hai đầu một đoạn mạch có biểu thức là (V) (t tính bắng s). Giá trị của u ở thời điểm t = 5 ms là ?

Giá trị đo của ampe kế nhiệt chỉ:

Cường độ dòng điện i = 4cos100πt (A) có pha tại thời điểm t là:

Điện áp ở hai đầu một đoạn mạch có biểu thức là (V) (t tính bắng s). Giá trị của u ở thời điểm t = 5 ms là ?

Một bóng đèn neon được mắc vào nguồn xoay chiều có điện áp   Đèn chỉ bật sáng khi điện áp đặt vào đèn vượt quá giá trị 100 (V). Trong 1 giây đèn này bật sáng bao nhiêu lần?

Điện áp tức thời ở hai đầu một đoạn mạch điện là. Điện áp hiệu dụng 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 24 to 28:

Few people now realize the reality of global warming and its effects on the world’s climate. Many scientists (24) _______ the blame for recent natural disasters on the increase in the world’s temperatures and are convinced that, more than ever before, the Earth is at (25) _______ from the forces of the wind, rain and sun. According to them, global warming is making extreme weather events, such as hurricanes and droughts, even more severe and causing sea levels all around the world to rise. Environmental groups are putting pressure on governments to take action to reduce the amount of carbon dioxide which is given (26) _______ by factories and power plants, thus attacking the problem at its source. They are in (27) _______ of more money being spent on research into solar, wind, and wave energy devices, which could then replace existing power (28) _______. Some scientists, however, believe that even if we stopped releasing carbon dioxide and other gases into the atmosphere tomorrow, we would have to wait several hundred years to notice the results. Global warming, it seems, is to stay.

Question 25:       

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 31 to 35:

The Internet has truly transformed how students do their homework. (31) ____homework today still means spending time in the library, it’s for a different reason. Rather than using books for research, students today are (32) ______to the Internet to download enormous amounts of data available online. In the past, students were limited to their school’s (33) _________ of books. In many cases, they got to the school library and found out that someone had already taken the books they needed. Nowadays, such inconvenience can be avoided since the Internet never runs out of information. Students, however, do have to (34)_____sure that the information they find online is true. Teachers have also benefited from the homework which is done on the Internet. They do not need to carry student's papers around with them any more. This is because online (35)______allow students to electronically upload their homework for their teachers to read and mark. Of course, this also means that students can no longer use the excuse that the dog ate their homework!

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 31 to 35:

The Internet has truly transformed how students do their homework. (31) ____homework today still means spending time in the library, it’s for a different reason. Rather than using books for research, students today are (32) ______to the Internet to download enormous amounts of data available online. In the past, students were limited to their school’s (33) _________ of books. In many cases, they got to the school library and found out that someone had already taken the books they needed. Nowadays, such inconvenience can be avoided since the Internet never runs out of information. Students, however, do have to (34)_____sure that the information they find online is true. Teachers have also benefited from the homework which is done on the Internet. They do not need to carry student's papers around with them any more. This is because online (35)______allow students to electronically upload their homework for their teachers to read and mark. Of course, this also means that students can no longer use the excuse that the dog ate their homework!

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 31 to 35:

The Internet has truly transformed how students do their homework. (31) ____homework today still means spending time in the library, it’s for a different reason. Rather than using books for research, students today are (32) ______to the Internet to download enormous amounts of data available online. In the past, students were limited to their school’s (33) _________ of books. In many cases, they got to the school library and found out that someone had already taken the books they needed. Nowadays, such inconvenience can be avoided since the Internet never runs out of information. Students, however, do have to (34)_____sure that the information they find online is true. Teachers have also benefited from the homework which is done on the Internet. They do not need to carry student's papers around with them any more. This is because online (35)______allow students to electronically upload their homework for their teachers to read and mark. Of course, this also means that students can no longer use the excuse that the dog ate their homework!

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 31 to 35:

The Internet has truly transformed how students do their homework. (31) ____homework today still means spending time in the library, it’s for a different reason. Rather than using books for research, students today are (32) ______to the Internet to download enormous amounts of data available online. In the past, students were limited to their school’s (33) _________ of books. In many cases, they got to the school library and found out that someone had already taken the books they needed. Nowadays, such inconvenience can be avoided since the Internet never runs out of information. Students, however, do have to (34)_____sure that the information they find online is true. Teachers have also benefited from the homework which is done on the Internet. They do not need to carry student's papers around with them any more. This is because online (35)______allow students to electronically upload their homework for their teachers to read and mark. Of course, this also means that students can no longer use the excuse that the dog ate their homework!

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 31 to 35:

The Internet has truly transformed how students do their homework. (31) ____homework today still means spending time in the library, it’s for a different reason. Rather than using books for research, students today are (32) ______to the Internet to download enormous amounts of data available online. In the past, students were limited to their school’s (33) _________ of books. In many cases, they got to the school library and found out that someone had already taken the books they needed. Nowadays, such inconvenience can be avoided since the Internet never runs out of information. Students, however, do have to (34)_____sure that the information they find online is true. Teachers have also benefited from the homework which is done on the Internet. They do not need to carry student's papers around with them any more. This is because online (35)______allow students to electronically upload their homework for their teachers to read and mark. Of course, this also means that students can no longer use the excuse that the dog ate their homework!

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 46 to 50:

When you read something in a foreign language, you frequently come across words you do not fully understand. Sometimes you (46) ______ the meaning in a dictionary and sometimes you guess. The strategy you adopt depends very much upon the degree of accuracy you require and the time at your disposal. If you are the sort of person who tends to turn to the dictionary frequently, it is (47) ______ remembering that every dictionary has its limitations. Each definition is only an approximation and one builds up an accurate picture of the meaning of a word only after meeting it in a (48) ______ of contexts. It is also important to recognize the special dangers of dictionaries that translate from English into your native language and vice versa. If you must use a dictionary, it is usually far safer to consult an English-English dictionary. In most exams you are not permitted to use a dictionary. (49) ______ you are allowed to use one, it is very time-consuming to look up words, and time in exams is usually limited. You are, therefore, forced to guess the meaning of unfamiliar words. When you come across unknown words in an exam text, it is very easy to panic. However, if you develop efficient techniques for guessing the meaning, you will overcome a number of possible problems and help yourself to understand far more of the text than you at first thought likely. Two strategies which may help you guess the meaning of a word are: using contextual clues, both within the sentence and outside, and making use of clues (50) ______ from the formation of the word.

Question 50:

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 46 to 50:

When you read something in a foreign language, you frequently come across words you do not fully understand. Sometimes you (46) ______ the meaning in a dictionary and sometimes you guess. The strategy you adopt depends very much upon the degree of accuracy you require and the time at your disposal. If you are the sort of person who tends to turn to the dictionary frequently, it is (47) ______ remembering that every dictionary has its limitations. Each definition is only an approximation and one builds up an accurate picture of the meaning of a word only after meeting it in a (48) ______ of contexts. It is also important to recognize the special dangers of dictionaries that translate from English into your native language and vice versa. If you must use a dictionary, it is usually far safer to consult an English-English dictionary. In most exams you are not permitted to use a dictionary. (49) ______ you are allowed to use one, it is very time-consuming to look up words, and time in exams is usually limited. You are, therefore, forced to guess the meaning of unfamiliar words. When you come across unknown words in an exam text, it is very easy to panic. However, if you develop efficient techniques for guessing the meaning, you will overcome a number of possible problems and help yourself to understand far more of the text than you at first thought likely. Two strategies which may help you guess the meaning of a word are: using contextual clues, both within the sentence and outside, and making use of clues (50) ______ from the formation of the word.

Question 49:

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:

Can we see (33)______ the earth is a globe? Yes, we can, when we watch a ship that sails out to sea. If we watch closely, we see that the ship begins (34)______. The bottom of the ship disappears first, and then the ship seems to sink lower and lower, (35)______ we can only see the top of the ship, and then we see nothing at all. What is hiding the ship from us? It is the earth. Stick a pin most of the way into an orange, and (36)______ turn the orange away from you. You will see the pin disappear, (37)______ a ship does on the earth.  

Question 36:

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:

Can we see (33)______ the earth is a globe? Yes, we can, when we watch a ship that sails out to sea. If we watch closely, we see that the ship begins (34)______. The bottom of the ship disappears first, and then the ship seems to sink lower and lower, (35)______ we can only see the top of the ship, and then we see nothing at all. What is hiding the ship from us? It is the earth. Stick a pin most of the way into an orange, and (36)______ turn the orange away from you. You will see the pin disappear, (37)______ a ship does on the earth.  

Question 37: