Fuse continuity check with a multimeter: On a 5 A circuit, you remove the fuse and measure its resistance. If the fuse is healthy (not blown), what should the meter read approximately?

Introduction / Context:
A fuse is intended to conduct with minimal resistance until a fault causes it to open. Measuring its resistance is a basic continuity test that confirms whether it is intact or blown.

Given Data / Assumptions:

• The fuse is removed from the circuit before measurement.
• A standard digital multimeter is set to measure resistance.
• The fuse rating (5 A) does not imply its resistance equals 5 ohms.

Concept / Approach:

An intact fuse is essentially a short conductor. Its resistance is very low (typically a fraction of an ohm). A blown fuse is an open circuit and reads infinite or out of range. Therefore, a good fuse should read very close to 0 ohms (some meters may show 0.0 or a small residual like 0.1–0.3 ohms due to lead resistance).

Step-by-Step Solution:

Verification / Alternative check:

Using the meter’s continuity beeper yields an audible tone on a good fuse and silence on a blown fuse; both methods agree with a near-zero ohm reading for a healthy fuse.

Why Other Options Are Wrong:

• 5.0 ohms: far too high; would drop excessive voltage and dissipate power.
• 0.5 ohms: higher than expected for most small fuses; while some very large fuses can be milliohms, typical readings are near zero on DMM.
• All of the above: cannot be correct since the readings are mutually exclusive.

Common Pitfalls:

Measuring in-circuit (parallel paths distort reading); forgetting to subtract lead resistance; assuming the ampere rating relates directly to ohmic value.

Final Answer:

0.0 (approximately zero ohms)