Which device uses a magnetized needle to indicate direction?

Which device uses a magnetized needle to indicate direction?

• A. Astrolabe
• B. Sextant
• C. Log tables and ephemerides
• D. Magnetic compass

Answer: (D)

Understanding how direction is shown on instruments is key here. A magnetized needle aligns with Earth’s magnetic field, so it points toward magnetic north and indicates direction directly—that’s exactly what a magnetic compass does. The other devices have different purposes: an astrolabe uses celestial angles to find latitude and time, a sextant measures angles between objects to help determine position, and log tables with ephemerides are reference tools for calculating positions but don’t display direction with a moving needle. So the device that uses a magnetized needle to indicate direction is the magnetic compass.

Understanding how direction is shown on instruments is key here. A magnetized needle aligns with Earth’s magnetic field, so it points toward magnetic north and indicates direction directly—that’s exactly what a magnetic compass does. The other devices have different purposes: an astrolabe uses celestial angles to find latitude and time, a sextant measures angles between objects to help determine position, and log tables with ephemerides are reference tools for calculating positions but don’t display direction with a moving needle. So the device that uses a magnetized needle to indicate direction is the magnetic compass.