With an ohmmeter connected into the circuit as shown, what will the ohmmeter read?

With an ohmmeter connected into the circuit as shown, what will the ohmmeter read?

• A. Infinite resistance
• B. 0 ohms
• C. 10 ohms
• D. 3 ohms

Answer: (C)

An ohmmeter measures resistance by applying a small current and reading the resulting voltage to determine the resistance between its two test leads. The displayed value is the equivalent resistance of everything connected between those leads, with power removed so there’s no other active current path. In the circuit shown, the path between the ohmmeter’s leads goes through a 3-ohm resistor in series with a 7-ohm resistor, and there aren’t any parallel paths between the leads. When components are in series, their resistances add directly, so the total seen by the meter is 3 ohms plus 7 ohms, which equals 10 ohms. Therefore the meter reads 10 ohms. If the circuit were open, you’d see infinite resistance; if there were a direct short across the leads, you’d see near zero ohms. Always ensure the circuit is de-energized before measuring resistance.

An ohmmeter measures resistance by applying a small current and reading the resulting voltage to determine the resistance between its two test leads. The displayed value is the equivalent resistance of everything connected between those leads, with power removed so there’s no other active current path.

In the circuit shown, the path between the ohmmeter’s leads goes through a 3-ohm resistor in series with a 7-ohm resistor, and there aren’t any parallel paths between the leads. When components are in series, their resistances add directly, so the total seen by the meter is 3 ohms plus 7 ohms, which equals 10 ohms. Therefore the meter reads 10 ohms.

If the circuit were open, you’d see infinite resistance; if there were a direct short across the leads, you’d see near zero ohms. Always ensure the circuit is de-energized before measuring resistance.