Một đoạn dây dẫn dài 10 cm đặt trong từ trường đều và vuông góc với vectơ cảm ứng từ. Dòng điện qua dây có cường độ 2 A. Lực từ tác dụng lên đoạn dây đó là 0,004 N. Cảm ứng từ trong đoạn dây có độ lớn là

Trong mặt phẳng \(O x y z\), cho ba điểm \(A(1 ; 2 ; 0), B(2 ; 1 ; 2), C(-1 ; 3 ; 1)\).

Phương trình mặt cầu bán kính \(B C\).

Các chất bán dẫn loại P và loại N chế tạo:

Choose the best answer to fill in the blank.

A lot of people like to play their records as loudly as possible. The (1) ____ is that the rest of the family and the neighbors often complain (2) ____ don't like the music. One (3) ____ to this problem is to wear headphones, but headphones are usually uncomfortable.

An arm-chair which has a record-player built into it has just been (4) ____ by a British engineer, Stephen Court.

The armchair looks like an ordinary armchair with high back. However, each of the two sides of the chair has three loudspeakers inside to reproduce middle and high sounds. Low sounds are reproduced by a pair of loudspeakers in a hollow (5) ____ under the seat. Anyone who sits in the chair hears sounds coming from all around his/her head.

Because we cannot tell the exact (6) ____ from which low sounds come, it doesn't (7) ____ that they come from underneath or behind. It is the higher sounds coming from the sides of the chair that create a stereo effect.

These sounds travel only a few inches to reach the listener's ears. (8) ____, it takes only a little power to make the music sound very loud. Only a small amount of sound leaks out from behind the chair into the room to (9) ____ others. Most of the sound is (10) ____ by the listeners.

Choose the best answer for question 9:

Cho hình chóp \(S. A B C D\) có đáy là hình vuông cạnh \(a\). Tam giác \(S A B\) đều và nằm trong mặt phẳng vuông góc với đáy. Gọi \(M, N\) lần lượt là trung điểm của \(S B, B C\).

Thể tích của hình chóp \(S. A B C D\) là

Một vật có khối lượng 1kg và động lượng 2kgm/s. Khi đó động năng của vật bằng

Thị trường gồm những nhân tố cơ bản nào dưới đây?

Mark the letter A, B, C, or D on your answer sheet to indicate the underlined part that needs correction in each of the following questions.

I’m becoming increasingly forgetable. Last week I locked myself out of the house twice.

Đạo đức trong  kinh doanh có vai trò như thế nào?

Sự tiến hoá của sinh giới được thể hiện qua đặc điểm nào dưới đây?

Các tuyến giao thông đường biển thường được biểu hiện bằng phương pháp gì?

Đâu là nhận định sai khi nói về thị trường?

Loại tài nguyên nào sau đây thuộc nhóm tài nguyên thiên nhiên vô hạn?

Theo Hiến pháp năm 2013, Nước Cộng hòa xã hội Chủ nghĩa Việt Nam gồm các cơ quan nào?

Đặc tính quan trọng nhất đảm bảo tính bền vững và ổn định tương đối của tổ chức sống là gì?

Although noise, commonly defined as unwanted sound, is a widely recognized form of pollution, it is very difficult to measure because the discomfort experienced by different individuals is highly subjective and, therefore, variable. Exposure to lower levels of noise may be slightly irritating, whereas exposure to higher levels may actually cause hearing loss. Particularly in congested urban areas, the noise produced as a by-product of our advancing technology causes physical and psychological harm, and detracts from the quality of life for those who are exposed to it.

Unlike the eyes, which can be covered by the eyelids against strong light, the ear has no lid, and is, therefore, always open and vulnerable; noise penetrates without protection. Noise causes effects that the hearer cannot control and to which the body never becomes  accustomeLoud noises instinctively signal danger to any organism with a hearing mechanism, including human beings. In response, heartbeat and respiration accelerate, blood vessels constrict, the skin pales, and muscles tense. In fact, there is a general increase in functioning brought about by the flow of adrenaline released in response to fear, and some of these responses persist even longer than the noise, occasionally as long as thirty minutes after the sound has ceased.

Because noise is unavoidable in a complex, industrial society, we are constantly responding in the same way that we would respond to danger. Recently, researchers have concluded that noise and our response may be much more than an annoyance. It may be a serious threat to physical and psychological health and well-being, causing damage not only to the ear and brain but also to the heart and stomach. We have long known that hearing loss is America's number one nonfatal health problem, but now we are learning that some of us with heart disease and ulcers may be victims of noise as well. Fetuses exposed to noise tend to be overactive, they cry easily, and they are more sensitive to gastrointestinal problems after birth. In addition, the psychic effect of noise is very important. Nervousness, irritability, tension, and anxiety increase affecting the quality of rest during sleep, and the efficiency of activities during waking hours, as well as the way that we interact with each other.

Based on the passage, how does noise affect psychological and physical health in industrial societies?