Cho một khung dây hình chử nhật ABCD có AB = 10 cm; BC = 20 cm, có dòng điện I = 4A chạy qua đặt trong một từ trường đều có các đường sức từ  song song với mặt phẵng chứa khung dây như hình vẽ. Biết B = 0,04 T. Xác định các véc tơ lực từ do từ trường đều tác dụng lên các cạnh của khung dây.

Choose A, B, C or D on your answer sheet to indicate the word that differs from the rest in the position of the main stress in each of the following questions.

A. adapt 

B. conference

C. reserve

D. prefer

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 45 to 54.

Although speech is the most advanced form of communication, there are many ways of communicating without using speech. Signals, signs, symbols, and gestures may be found in every known culture. The basic function of signal is to impinge upon the environment in such a way that it attracts attention, as, for example, the dots and dashes of a telegraph circuit. Coded to refer to speech, the potential for communication is very great. Less adaptable to the codification of words, signs also contain meaning in and of themselves. A stop sign or a barber pole conveys meaning quickly and conveniently.

Symbols are more difficult to describe than either signals or signs because of their intricate relationship with the receiver’s cultural perceptions. In some cultures, applauding in a theater provides performers  with an auditory symbol of approval. Gestures such as waving and handshaking also communicate certain cultural messages.

Although signals, signs, symbols, and gestures are very useful, they do have a major disadvantage in communication. They usually do not allow ideas to be shared without the sender being directly adjacent  to the receiver. Without an exchange of ideas, interaction comes to a halt. As a result, means of communication intended to be used for long distances and extended periods must be based upon speech. To radio, television, and the telephone, one must add fax, paging systems, electronic mail, and the Internet, and no one doubts but that there are more means of communication on the horizon.

The word “potential” in paragraph 1 could be   replaced by_____________.

A. advantage                  

B. possibility                           

C. organization    

D. range

Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the following questions.

The word robot first appeared in a 1921 stage play by Czech writer Karel Capek. In the play, a man makes a machine that can think, which he calls a robot and which ends up killing its owner. In the 1940s, the American science fiction writer Isaac Asimov wrote a series of stories about robots and invented the term robotics, the science of robots. Meanwhile, in the real world, the first robots were developed by an engineer, Joseph F. Engelberger, and an inventor, George C. Devol. Together they started Unimation, a manufacturing company that produces the first real robot in 1961, called the Unimate. Robots of this type were installed at a General Motors automobile plant and proved to be a success. They worked reliably and saved money for General Motors, so other companies were soon acquiring robots as well.

These industrial robots were nothing like the terrifying creatures that can often be seen in science fiction films. In fact, these robots looked and behaved nothing like humans. They were simply pieces of computer-controlled machinery, with metal “arms” or “hands”. Since they were made of metal, they could perform certain jobs that were difficult or dangerous for humans, particularly jobs that involve high heat. And since robots were tireless and never got hungry, sleepy, or distracted, they were useful for tasks that would be tiring or boring for humans. Industrial robots have been improved over the years, and today they are used in many factories around the world. Though the use of robots has meant the loss of some jobs, at the same time other jobs have been created in the design, development, and production of the robots.

Rise of the Robots, Silicon Valley Entrepreneur, Martin Ford, 1988.

What is Unimation?

A. It’s the name of a robot inventor

B. It’s the name of a robot

C. It’s a robot making program

D. It’s the producer of the first robot