Предмет: Физика, автор: 375298

найдите количество электронов,протонов и нейтронов в изотопе полония 209/84Ро

jengorbunow201: нейтронов равно 209-84

jengorbunow201: забыл написать

Ответы

Автор ответа: jengorbunow201

протонов 84 , электронов 84 и нейтронов 125

375298: как вы это посчитали

jengorbunow201: короче у тебя написано 84 это число протонов, а число протонов равно числу электронов потом из 209 вычитаем 84 и получаем нейтронов

375298: всё поняла

375298: спасибо))

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The PSTN (the public switched telephone networks) we have been describing has a star configuration. Local loops (usually one per subscriber) terminate in a CO (central-office). This CO completes connections from one local loop to another local loop or from one local loop to a trunk that terminates on some other CO. This CO has gone through a number of fundamental technological changes. The manual system required, of course, constant attention from operators. In the late 1800s, telephone calls were connected manually at the CO. When a call came in, an attendant would plug into a horizontal bar line. He then would yell to the operator who handled the customer being called, and that second operator would connect to the bar and finish setting up the call. When the call was completed, another operator would yell to all in the room that the line was clear again. The step – by – step system, which is still in operation in many parts of country, utilized that is known as the Stronger switch. The intelligence in the system was located in relays mounted on each switch. The switch itself responded to the dial pulses of the rotary dial.

The crossbar system was still electromechanical in nature, but the intelligence of the system was separated from the actual switch. Thus, this common control could be used repeatedly to set up and tear down calls and never sit idle.

When electronics came along, the electromechanical control of the common control system was replaced with electronics, and the network, or matrix, was usually replaced with tiny glass – encapsulated reed switches. Hence, only a part of the switch was electronic. In the next generation, the stored program operation of a digital computer was applied to the switch, the talking path was no longer an electrically continuous circuit; rather the speech being carried was digitized into a stream of “1s” and “0s.” Notice that this final generation depicted a significant change from the previous generations in that there was no longer an electrical talking path through the switch. We were, in fact, operating in a digital (rather than analog) domain.

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