🔍 Key Concepts

• Relationship between Ohm’s Law (E = I × R) and different electrical quantities • What an ammeter, voltmeter, and ohmmeter each measure • When you would test a circuit with power OFF vs. power ON

💭 Think About

• Think about which electrical quantity is represented by the symbol R in Ohm’s Law and which unit goes with it. • Ask yourself: an ohmmeter is usually used with the circuit de-energized; which of these four choices would you normally measure with power removed? • Match each instrument: ammeter, voltmeter, ohmmeter, wattmeter, to current, voltage, resistance, and power—then see which one fits the ohmmeter.

✅ Before You Answer

• Be sure you know the units for current, voltage, resistance, and power (amps, volts, ohms, watts). • Confirm which quantity changes when you add more load to a circuit without changing the supply voltage. • Verify which measuring device is connected in series vs. in parallel vs. used on an isolated component.