What is the typical voltage provided by a USB connection?

• A. 3 Volts
• B. 5 Volts
• C. 12 Volts
• D. 1 Volt

Answer: (B)

USB supplies a nominal 5 volts on its power line. This standard voltage is what devices expect when they’re plugged into a USB port, with typical tolerance around about 4.75 to 5.25 V. The amount of current available depends on the USB version and port design (USB 2.0 up to about 500 mA, USB 3.0 up to about 900 mA, and newer arrangements like USB-C with Power Delivery can negotiate higher voltages and currents). The key point is that the fixed, standard voltage for USB connections is 5 volts, which is why 5 volts is the best answer.