a specially designed voltmeter, which can be used to measure the electrical potential difference between very high resistance voltaic cells, under conditions of essentially, zero current flow in the measuring circuit
An instrument with a digital display that measures the PH of a solution. The device must be calibrated with a solution of known PH. A properly calibrated PH meter is more accurate than PH paper because visual comparison of colors is not required.
A pH meter is an electronic instrument used to measure the p H (acidity or basicity) of a liquid (though special probes are sometimes used to measure the pH of semi-solid substances, such as cheese). A typical pH meter consists of a special measuring probe (a glass electrode) connected to an electronic meter that measures and displays the pH reading.