Which statement about voltage is true?

• A. Voltage is measured in volts (V) or kilovolts (kV).
• B. Voltage is measured in amperes.
• C. Voltage is the same as resistance.
• D. Voltage is the energy per photon.

Answer: (A)

Voltage is the electrical potential difference that drives current. It is measured in volts, with kilovolts representing 1000 volts. This is the unit used to describe the push behind electron movement, and in radiology, tube voltage is often specified as kVp, which helps determine the energy range of emitted X-ray photons. Amperes measure current, not voltage. Resistance is measured in ohms, not voltage. Photon energy comes from the photon’s frequency (E = hf) and, while the tube voltage influences the maximum energy of generated photons, it is not itself the energy per photon. So the true statement is that voltage is measured in volts or kilovolts.