Which unit is used to measure electrical power?

Which unit is used to measure electrical power?

• A. Watts
• B. Joules
• C. Newton meters
• D. Ohms

Answer: (A)

Power in an electrical system is the rate at which energy is transferred or used. Because power is energy per unit time, its unit is the watt, which is defined as one joule per second. In circuits, power can be found with P = V × I, so the amount of power depends on the voltage across and the current through the component, measured in watts. For example, a device using 3 amperes at 120 volts consumes 360 watts of power. Joules measure energy, not rate, so they describe how much energy is transferred, not how fast. Newton meters are a torque unit used for rotational work, not for electrical power. Ohms measure resistance, not power. So watts are the appropriate unit for electrical power.

Power in an electrical system is the rate at which energy is transferred or used. Because power is energy per unit time, its unit is the watt, which is defined as one joule per second. In circuits, power can be found with P = V × I, so the amount of power depends on the voltage across and the current through the component, measured in watts. For example, a device using 3 amperes at 120 volts consumes 360 watts of power.

Joules measure energy, not rate, so they describe how much energy is transferred, not how fast. Newton meters are a torque unit used for rotational work, not for electrical power. Ohms measure resistance, not power. So watts are the appropriate unit for electrical power.