Field Lines Tilt at Every Latitude

In the picture

1. 1The curved field line arcing from pole to pole around the globe.
2. 2The straight silver rod lying flat at the equator, side by side with the field line above it.
3. 3The sea turtle sitting on the globe over northern Europe.
4. 4The shaded amber wedge between the northern rod and the field line.

Examples

• A dip needle balanced on a sideways pivot: carry it further north and one end points more and more downward.
• The compass app on your phone uses a magnetic sensor that reads the field in three directions, not just left and right.

Quiz: Field Lines Tilt at Every Latitude (Age 14)

1. 1

   Near the equator, Earth’s magnetic field lines:

   • plunge almost straight down into the surface
   • run almost flat along the surface
   • point straight up away from the surface
2. 2

   A sea turtle senses the magnetic field lines dipping steeply into the surface beneath it. What can it reasonably conclude?

   • It is somewhere near the equator
   • It is far from the equator, closer to a pole
   • It is in deep water rather than shallow water
3. 3

   Why is the tilt of the field lines useful to an animal as a natural signpost?

   • Because the tilt changes with latitude, so each angle matches a rough distance north or south
   • Because the tilt is the same everywhere, giving one fixed reference direction
   • Because the tilt changes with the time of day, acting like a clock

The answers, each with its explanation, are in the app. This lesson has left the free week, so its quiz is part of the subscription.