phy果d CRO點睇GA?

先看以下 CRO 的用法:
Usage of CRO:
(I) Measurement of current

Connect the input of a CRO across a standard resistor (with known resistance) which is in series with the circuit as shown below.

圖片參考：http://i117.photobucket.com/albums/o61/billy_hywung/CRO1.jpg

【此圖乃本人自製圖片，未經本人同意勿擅自連結或使用】
Voltage reading shown on the CRO screen and current can be obtained from I = V/R.
(II) Waveform display

Time base must be switched on in accordance to the frequency of the signal.
Connect the signal to the Y-input of CRO.
Waveform is displayed below with a sinusoidal and square waves as examples:

圖片參考：http://i117.photobucket.com/albums/o61/billy_hywung/CRO3.jpg
Square
【此圖乃本人自製圖片，未經本人同意勿擅自連結或使用】
(III) Measurement of period and frequency of a signal

Time base must be switched on in accordance to the frequency of the signal.
Connect the signal to the Y-input of CRO.
Period T is given by time base × length of 1 cycle and frequency f = 1/T. An example of trace is shown below:

圖片參考：http://i117.photobucket.com/albums/o61/billy_hywung/CRO4.jpg

【此圖乃本人自製圖片，未經本人同意勿擅自連結或使用】
(IV) Measurement of phase difference between 2 same frequency signals

Dual-trace (double beam) CRO must be used.
Time base must be switched on in accordance to the frequency of the signal.
Connect the signals to the 2 Y-inputs of CRO.
An example of trace is given below:

圖片參考：http://i117.photobucket.com/albums/o61/billy_hywung/CRO5.jpg

【此圖乃本人自製圖片，未經本人同意勿擅自連結或使用】
For this example, V2 is leading V1 or conversely, V1 is lagging V2. Moreover the phase difference θ is given by:
θ/2π = t/T
由以上用途可見, 當 time base on 時, X 軸所表示的為時間差距 (差幾多視乎個 time base set 了幾多). 而 Y 軸所表示的為輸入電壓的值, 至於幾多亦係視乎個 Voltage gain set 了幾多.