串聯.... 並聯.....

Ammeter is used to measure current passing through a curtain path and current is physical exist. Thus, ammeter should be connected in series for measurment. Just like if you wanna to measure the water passing through a tube or pipe.

Voltmeter is used to measure the potential difference between two points of a circuit. However, potential difference is virtual and is not physical exist, it is required to connected in parallel when measurement. Just like if you wanna to measure the pressure of water in a pipe, if you connect pipe and the measurement equipment in series, water will goes in and you never able to measure the presure.

因為串聯流過的電流是一樣,所以要用安培計,安培計是用來測量一個線路上(即電阻)所流過的電流

因為並聯所得到的電壓是一樣,所以用伏特計,伏特計是用來測量一個線路上(即電阻)所得到的電壓

若果安培計放在並聯上,安培計會失效
若果伏特計放在串聯上,伏特計會失效

因為ammeter係suppose to be無resistance, 如果串聯會short circuit

similarly, voltnmeter係假設佢resistance無限大，如果in series, 所有voltage都會比佢take晒~