An AC voltmeter is a device that measures the (peak) oscillating current I0 across a large resistor R0 that is attached to leads whose tips, 1 and 2, may be connected to some other circuit. The reading of the voltmeter (if properly calibrated) is Vmeter = I0(R0 + Rleads) where Rleads R0. AC voltmeters typically report the root-mean-square voltage Vrms = I0(R0 +Rleads)/ √ 2 rather than I0(R0 +Rl...

We have developed a general electron paramagnetic resonance (EPR) method to measure electrostatic potential at spin labels on proteins to millivolt accuracy. Electrostatic potential is fundamental to energy-transducing proteins like myosin, because molecular energy storage and retrieval is primarily electrostatic. Quantitative analysis of protein electrostatics demands a site-specific spectrosc...

1. Do living organisms possess steady state, or direct current, potential differences? 2. Can these potential differences be measured in such a way as to be free from the usual ambiguities of electrical measurement, i.e., can the determination of potential differences be made independently of resistance changes and current flow? 3. Do these potential differences reflect an unorganized chaos or ...

An electrostatic voltmeter possessing several unique features is described. The size is a minimum for such instruments, since the potential difference is applied to two electrodes, the geometrical arrangement of which is analogous to concentric spheres. The inner electrode is supported on the end of an insulating bushing introduced through the outer electrode, which is a metal can. The inner el...