Nanoampere to Franklin second

Chip designers optimize deep-sleep modes to leak only 1–100 nA so a coin cell battery (225 mAh) can power the device for 5–10 years without replacement. Every nanoampere matters in IoT sensors deployed in remote locations where battery swaps are impractical or impossible.

Yes — picoammeters and source-measure units (SMUs) from Keithley or Keysight resolve currents down to 0.01 nA. The trick is shielding: at nanoampere levels, even humidity on a PCB trace or triboelectric effects from cable movement can introduce errors larger than the signal itself.

Individual ion channels in cell membranes pass about 2–10 picoamperes each, but clusters of channels in a patch-clamp experiment produce nanoampere signals. Electrochemical glucose sensors generate 50–500 nA proportional to blood sugar levels. Neural signal electrodes also detect nA-scale biocurrents.

At nanoampere levels, leakage through PCB substrates, capacitor dielectrics, and transistor junctions becomes significant. High-impedance analog circuits must use guarded traces, Teflon standoffs, and low-leakage components. A fingerprint on a circuit board can introduce 1–10 nA of leakage from moisture absorption.

One nanoampere is about 6.24 billion electrons per second (6.24 × 10⁹ e/s). That sounds like a lot, but it is literally a billionth of the electron flow in a one-ampere current. Counting individual electrons at this rate is the basis of quantum current standards being developed at national metrology labs.

Franklin (1706–1790) was the American polymath who proved lightning is electrical with his famous kite experiment in 1752. He introduced the convention of "positive" and "negative" charge that we still use today. He arbitrarily assigned positive to the charge on glass rubbed with silk — which turned out to be a deficit of electrons, giving us the unfortunate convention that current flows opposite to electron motion.

The roentgen (R) was defined in 1928 as the radiation exposure producing 1 ESU of charge (1 franklin ≈ 3.336 × 10⁻¹⁰ C) per cm³ of dry air at STP. This CGS-era definition stuck because radiation safety regulations were already built around it. Even though the SI gray replaced the roentgen for dosimetry, the roentgen — and its franklin-based definition — persists in US regulatory and medical imaging contexts.

The legacy unit of radiation exposure, the roentgen (R), is defined as the amount of X-ray or gamma radiation that produces 1 esu of charge (1 franklin) per cubic centimeter of dry air at STP. This definition dates from the 1920s when CGS-ESU was standard. Modern dosimetry uses grays and sieverts, but the roentgen and its franklin-based definition persist in some medical and regulatory contexts.

One Fr/s is about 0.33 nanoamperes — less current than a sleeping microcontroller draws. To equal the 1 A flowing through a phone charger cable, you would need about 3 billion franklins per second. The unit is spectacularly impractical for anything beyond electrostatics calculations.

Sort of. He labelled the charge on glass rubbed with silk as "positive," not knowing it was caused by removing electrons. When Thomson discovered the electron in 1897, it turned out electrons carry what Franklin called negative charge. So conventional current flows from + to −, opposite to actual electron flow. Engineers and physicists have lived with this "mistake" for over 250 years.