🔍 Key Concepts

• Watt is a unit of power, and electric power in a DC circuit is calculated using voltage and current • How voltage is measured in a circuit (connection method of a voltmeter) • How current is measured in a circuit (connection method of an ammeter)

💭 Think About

• Think about what two electrical quantities must be known so that power (watts) can be determined in a circuit. • Consider whether a wattmeter needs to sense the same way as a voltmeter, an ammeter, or a combination of the two. • Ask yourself: does power measurement require the instrument to be in the actual current path, across the load, or both?

✅ Before You Answer

• Review that P = V × I and what that means for how the device must be connected. • Compare how a voltmeter is connected versus how an ammeter is connected, and which combination would let you determine power. • Confirm whether the chosen option would allow the meter to see both the current through and voltage across the load at the same time.