If a D.C. motor hums, but does not run when...

Question 1 / 270705eccefa3bacbc34ba4d4806c

Question 1 of 270705eccefa3bacbc34ba4d4806c

If a D.C. motor hums, but does not run when energized, which of the listed conditions could exist?

Question 1 of 27070

If a D.C. motor hums, but does not run when energized, which of the listed conditions could exist?

🔍 Key Concepts

• How a D.C. motor starts turning (it needs both power and freedom to rotate) • Difference between an electrical open/trip and a mechanical jam • What would happen if a motor has power applied but cannot physically turn

💭 Think About

• If a motor is humming, what does that tell you about whether it is getting electrical power? • Which listed conditions would completely prevent current from reaching the motor, and would you still get a humming sound in those cases? • Which condition would allow voltage to be applied but physically resist or stop the rotation of the shaft?

✅ Before You Answer

• Identify which options represent no power to the motor versus power but mechanical resistance • Ask yourself: in which case would I hear a hum but see no rotation? • Verify that a tripped overload or blown fuse usually interrupts power, affecting whether the motor can hum at all.

Question 1 of 27070

If a D.C. motor hums, but does not run when energized, which of the listed conditions could exist?

No load on the motor

Blown fuse or tripped circuit breaker

Tripped overload

Tight bearings/frozen shaft