Which instrument would you use to determine the cardinal directions?

Which instrument would you use to determine the cardinal directions?

• A. Ruler
• B. Compass
• C. Thermometer
• D. Altimeter

Answer: (B)

To determine cardinal directions, you need a device that responds to Earth's magnetic field. A compass uses a magnetized needle that aligns with the field and points toward magnetic north, which lets you determine north, and from there the other directions—south, east, and west. The other tools measure things unrelated to direction: a ruler gauges length, a thermometer measures temperature, and an altimeter measures altitude. That’s why the compass is the instrument used to determine cardinal directions.

To determine cardinal directions, you need a device that responds to Earth's magnetic field. A compass uses a magnetized needle that aligns with the field and points toward magnetic north, which lets you determine north, and from there the other directions—south, east, and west. The other tools measure things unrelated to direction: a ruler gauges length, a thermometer measures temperature, and an altimeter measures altitude. That’s why the compass is the instrument used to determine cardinal directions.