Electromagnetic induction and the generator · 电磁感应与发电机
| English | 中文 | Pinyin · 拼音 |
|---|---|---|
| generator/ˈdʒenəreɪtə/ | 发电机 | fā diàn jī |
| electromagnetic induction/ɪˌlektrəʊməɡˈnetɪk ɪnˈdʌkʃn/ | 电磁感应 | diàn cí gǎn yìng |
| induced/ɪnˈdjuːst/ | 感应的 | gǎn yìng de |
| a.c. generator/ˌeɪ ˈsiː ˈdʒenəreɪtə/ | 交流发电机 | jiāo liú fā diàn jī |
| slip rings/slɪp rɪŋz/ | 滑环 | huá huán |
| brushes/ˈbrʌʃɪz/ | 电刷 | diàn shuā |
Making electricity from movement
- The motor effect turns electricity into movement. Run it backwards — movement into electricity — and you have a generator 发电机.
- This is electromagnetic induction 电磁感应, and it powers almost every power station on Earth.
- Let's see how movement makes a current.
从运动产生电
- 电动机效应把电变成运动。反过来运行它——运动变成电——你就有一个发电机(generator)。
- 这是电磁感应(electromagnetic induction),它为地球上几乎每个发电站提供动力。
- 让我们看看运动如何产生电流。
Electromagnetic induction
- When a wire moves across a magnetic field — or the field through a coil changes — an e.m.f. is induced 感应的.
- If the wire is part of a complete circuit, that e.m.f. drives a current.
- Move a magnet in and out of a coil joined to a meter, and the needle flicks.
电磁感应
- 当一根导线横穿一个磁场——或穿过一个线圈的场变化时——一个电动势被感应。
- 如果导线是一个完整电路的一部分,那个电动势驱动一个电流。
- 把一块磁铁在一个连接到仪表的线圈中进出移动,针就跳动。
The generator · 发电机
V = a sin(bt)
A spinning coil induces a sinusoidal voltage — the AC output. · 一个旋转的线圈感应一个正弦电压——交流输出。
How can you induce a current in a coil with a magnet? · 你如何用一块磁铁在一个线圈中感应一个电流?
A current is induced only when the field through the coil is changing — for example by moving the magnet. · 只有当穿过线圈的场在变化时电流才被感应——例如通过移动磁铁。
A magnet held still inside a coil induces a steady current. · 一块静止放在线圈内的磁铁感应一个稳定的电流。
There must be movement or a changing field. A still magnet causes no change, so no e.m.f. is induced. · 必须有运动或一个变化的场。一块静止的磁铁不造成变化,所以没有电动势被感应。
Making the induced e.m.f. bigger
- The induced e.m.f. is bigger when you use a stronger magnet, move faster, or use more turns on the coil.
- There must be movement or change — a magnet sitting still inside a coil induces nothing.
- The induced e.m.f. always acts to oppose the change that causes it.
An a.c. generator 交流发电机
使感应电动势更大
- 当你用一块更强的磁铁、移动更快,或在线圈上用更多匝数时,感应电动势更大。
- 必须有运动或变化——一块静止在线圈内的磁铁感应不出任何东西。
- 感应电动势总是作用来反对造成它的变化。
一个交流发电机
Which change makes the induced e.m.f. bigger? · 哪个改变使感应电动势更大?
A stronger magnet, faster movement, or more turns all increase the induced e.m.f. · 一块更强的磁铁、更快的运动,或更多匝数都增加感应电动势。
Match each idea to what it means. · 把每个想法与它的含义配对。
Each item links the term to its correct meaning. · 每一项把术语与它正确的含义联系。
The a.c. generator
- An a.c. generator spins a coil in a magnetic field. As it turns, the field through the coil keeps changing, so an alternating e.m.f. is induced.
- Slip rings 滑环 and carbon brushes 电刷 carry the current out while the coil keeps turning.
- The e.m.f. is largest when the coil is flat (cutting field lines fastest) and zero when it is upright — giving a wave-shaped (sine) output.
交流发电机
- 一个交流发电机(a.c. generator)在一个磁场中旋转一个线圈。当它转动时,穿过线圈的场不断变化,所以一个交变电动势被感应。
- 滑环(slip rings)和碳电刷(brushes)在线圈持续转动时把电流带出来。
- 当线圈是平的(最快地切割场线)时电动势最大,当它直立时为零——给出一个波形(正弦)输出。
The output of a simple a.c. generator is: · 一个简单的交流发电机的输出是:
As the coil spins, the field through it changes back and forth, giving an alternating (sine-wave) e.m.f. · 当线圈旋转时,穿过它的场来回变化,给出一个交变(正弦波)电动势。
What do the slip rings and brushes do in an a.c. generator? · 滑环和电刷在一个交流发电机中做什么?
Slip rings and brushes keep a sliding contact, carrying the a.c. out without the wires twisting. (A commutator, by contrast, reverses the current — that is for a motor or d.c. generator.) · 滑环和电刷保持一个滑动接触,把交流带出而导线不缠绕。(相反,一个换向器反转电流——那是用于一个电动机或直流发电机。)
You've got it
- moving a wire across a field (or changing the field through a coil) induces an e.m.f.
- bigger e.m.f.: stronger magnet, faster movement, more turns — and there must be change
- an a.c. generator spins a coil → alternating e.m.f.; slip rings + brushes carry it out
- output is a sine wave: max when the coil is flat, zero when upright
你掌握了
- 把一根导线横穿一个场(或改变穿过一个线圈的场)感应一个电动势
- 更大的电动势:更强的磁铁、更快的运动、更多匝数——而且必须有变化
- 一个交流发电机旋转一个线圈 → 交变电动势;滑环 + 电刷把它带出来
- 输出是一个正弦波:线圈平时最大,直立时为零