山东信息职业技术学院电子工程系
Text Diode
A diode is a nonlinear electrical device allowing current to move through it in one direction with far greater ease than in the other and usually acting as a one-way valve for current. The most common kind of diode in modern circuit design is the semiconductor diode, although other diode technologies exist. Semiconductor diodes are symbolized in schematic diagrams such as Fig. 2-1.
Oddly enough, the direction of the diode symbol's “arrowhead”points against the direction of electron flow. This is because the diode symbol was invented by engineers, who predominantly use conventional flow notation in their schematics, showing current as a flow of charge from the positive (+) side of the voltage source to the negative (-). This convention holds true for all semiconductor symbols possessing “arrowheads”. The arrow points in the permitted direction of conventional flow, and against the permitted direction of electron flow.
山东信息职业技术学院电子工程系
When the polarity of the battery is such that electrons are allowed to flow through the diode, the diode is said to be forward-biased. Conversely, when the battery is “backward”and the diode blocks current, the diode is said to be reverse-biased. A diode may be thought of as like a switch: “closed” when forward-biased and “open” when reverse-biased. oddly enough：稀奇的是
山东信息职业技术学院电子工程系
New Words and Expressions
diode [ 'daiəud ]
二极管
nonlinear [ nɔn'liniə ]
非线性
-way 单向的
valve [ væ lv ]
阀门
semiconductor [ˌsemikən'dɔktə ]
半导体
schematic [ ski:'mæ tik ]
冶金
silicon [ 'silikən ]
硅
n-type
N型
p-type P型
juxtaposed [ˌ dʒʌkstə'pəuzd ]
紧靠的
ohmmeter [ 'əum ˌ mi:tə ]
欧姆表
qualitatively [ 'kwɔlitətivli]
定性地
purpose
目的
expect
期望
military [ 'militəri ]
军用
civilian [ si'viljən ]
民用
peak [ pi:k ] 峰值
clamper [ 'klæmpə ] 钳子
rectification
整流
photic [ 'fəutik ]
光
decoration [ˌ dekə'reiʃən ]
装潢、装饰
In Fig. 2-1, arrows indicate the direction of electroncurrent flow.
山东信息职业技术学院电子工程系
When placed in a simple battery-lamp circuit, the diode will either allow or prevent current through the lamp, depending on the polarity of the applied voltage. (Fig. 2-2) (a) Current flow is permitted; the diode is forward biased. (b) Current flow is prohibited; the diode is reversed biased.
原理图
symbol [ 'simbəl ]
图表
arrows 箭头
battery [ 'bætəri ]
电源
lamp [ læ mp ]
灯
permit [ pə'mit ]
准许
prohibit [ prəu'hibit ]
禁止
polarity [ pəu'lærəti ]
极性
Conversely
相反
switch [ switʃ ]
开关
oddly [ 'ɔdli ]
奇怪地
invent
发明
山东信息职业技术学院电子工程系
predominantly
占主导地位的
conventional [ kən'venʃənəl ] 习惯的、传统的
notation [ nəu'teiʃən ]
符号、标记
metallurgically [ˌ melə'lə:dʒikli ]