What are the units used to measure power in ultrasound?

What are the units used to measure power in ultrasound?

• A. Watts
• B. Joules
• C. Newtons
• D. Volts

Answer: (A)

Power is the rate at which acoustic energy is delivered, so it’s measured in watts. One watt equals one joule per second, reflecting energy transfer per unit time. Joules quantify total energy, not the rate, so they aren’t the right unit for power. Newtons measure force, and volts measure electrical potential—neither directly describes how quickly energy is transferred in the ultrasound beam. In practice, you may also see intensity given in watts per square centimeter, which is power per area, but the fundamental unit for power remains the watt.

Power is the rate at which acoustic energy is delivered, so it’s measured in watts. One watt equals one joule per second, reflecting energy transfer per unit time. Joules quantify total energy, not the rate, so they aren’t the right unit for power. Newtons measure force, and volts measure electrical potential—neither directly describes how quickly energy is transferred in the ultrasound beam. In practice, you may also see intensity given in watts per square centimeter, which is power per area, but the fundamental unit for power remains the watt.