What should the resistance reading be when the shunt resistor is operational?

• A. Between 0 and 10 Ohms
• B. Between 100 and 200 Ohms
• C. Between 450 and 550 Ohms
• D. Between 1k and 2k Ohms

Answer: (C)

A shunt resistor is used to create a precise, known resistance so that the small voltage drop across it can be used to infer current. When a shunt is working properly, the resistance you read across its terminals should match its rated value, within tolerance. In this case, the shunt is expected to be about 500 ohms, so you should see a reading in the 450–550 ohm range.

If the reading were much lower, like 0–10 ohms, it would suggest a shorted or bypassed shunt. If it were much higher, such as 100–200 ohms or 1k–2k ohms, that would indicate an abnormal condition or that a different component is being measured. So the reading around 500 ohms shows the shunt is intact and functioning as intended.