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# The magnet used in a magnetic compass is usually called:

A compass' small, lightweight magnet, or needle, is balanced on a nearly frictionless pivot point.

# How do you know when the needle is pointing north?

One end of the needle is often marked "N," for north, or colored in some way to indicate that it points toward north.

# Why does a compass have a lightweight magnet and a frictionless bearing?

The Earth's diameter is about 8,000 miles (12,875 kilometers), which is a long way for the planet's magnetic field to go before affecting your compass. That's why a compass has a lightweight magnet and a frictionless bearing -- otherwise, there just isn't enough strength in the Earth's magnetic field to turn the needle.

# According to a theory, what causes the Earth's magnetic forces?

Convection caused by heat radiating from the Earth's core, along with the rotation of the Earth, may be what causes the liquid iron of the Earth's core to rotate and create a magnetic field.

# What's one way to change a needle (or other wirelike piece of steel) into a magnet?

You can magnetize a needle by stroking it with a magnet 10 to 20 times.

# Ships and airplanes use what type of compass?

Because of the trouble encountered by magnetic compasses on moving platforms, many ships and planes instead use gyroscopic compasses.

# What's one of the problems encountered by magnetic compasses on moving platforms?

Not only do magnetic compasses correct themselves slowly when the platform turns, but they also must be kept level to work properly.

# What keeps a gyrocompass pointing in the same direction even when moved or rotated?

A spinning gyroscope inside the compass, fueled by a small motor, keeps the needle pointing north even in rough seas or turbulence.

# How is the needle of a gyrocompass initially oriented north?

The axis of a gyrocompass is pointed north using a magnetic compass as a reference. Magnetic compasses are also periodically used to correct any errors picked up by the gyrocompass.

# Which of the following do you not need in order to make your own compass?

To make your own compass, all you have to do is place a magnetized needle on a lightweight floating material in a dish of water. The needle will slowly point toward north.

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Image: refer to hsw