Compass needle
Definition
A compass needle is a small, magnetized needle that aligns itself with the Earth's magnetic field, pointing towards the magnetic north pole. It is used in navigation and in experiments to demonstrate the direction of magnetic fields.
5 Must Know Facts For Your Next Test
- The compass needle aligns itself with the Earth's magnetic field due to its own magnetism.
- It points towards the magnetic north pole, which is different from the geographic North Pole.
- The behavior of a compass needle can demonstrate the presence and direction of an external magnetic field.
- In historical context, compass needles were crucial for navigation before the advent of modern technology.
- The deflection of a compass needle near a current-carrying conductor demonstrates the interaction between electric currents and magnetic fields (Ampère's law).
Review Questions
- Why does a compass needle align itself with Earth's magnetic field?
- What is the significance of a compass needle pointing towards the magnetic north pole?
- How can a compass needle be used to demonstrate Ampère's law?
"Compass needle" appears in:
Related terms
Magnetic Field: A region around a magnetic material or moving electric charge within which the force of magnetism acts.
Magnetic Declination: The angle on the horizontal plane between magnetic north (the direction the north end of a compass needle points) and true north.
Ampère's Law: $$\oint \mathbf{B} \cdot d\mathbf{l} = \mu_0 I$$, which states that for any closed loop path, the sum of lengths times the magnetic field in those lengths is proportional to the electric current enclosed in that loop.
