Unit 4: Magnetism Flashcards
Is the north magnetic pole of the earth a north polarity or a south polarity?
South polarity. The magnetic north pole is located near the southern polar axis and the magnetic south pole is located near the northern polar axis. The reason that the geographic poles (axes) are called north and south is because the north pole of a compass needle points in the direction of the north geographic pole.
What were early natural magnets known as?
Early natural magnets were known as lodestones.
The south pole of one magnet is brought close to the south pole of another magnet. Will the magnets repel or attract each other?
Like poles of a magnet repel each other, and unlike poles attract each other.
How can the polarity of an electromagnet be determined if the direction of current flow is known?
The polarity of an electromagnet can be determined using the left-hand rule. When the fingers of the left hand are placed around the windings in the direction of electron current flow, the thumb points to the north magnetic pole.
What is flux density?
In the English system of measure, magnetic strength is measured in a term called flux density.
What is permeability?
Permeability is a measure of a material’s ability to become magnetized.
What is reluctance?
Reluctance is resistance to magnetism.
What is saturation?
Saturation occurs when all the molecules of the magnetic material are lined up. If the current flow in an electromagnet is continually increased, the magnet eventually reaches a point where its strength increases only slightly with an increase in current.
What is coercive force?
Coercive force is a measure of a material’s ability to retain magnetism.
What is residual magnetism?
The amount of magnetism left in a material after the magnetizing force has stopped is called residual magnetism.
A force of 1 ounce is equal to how many dynes?
One dyne is equal to 1/27,800 of an ounce, or it requires 27,800 dynes to equal a force of 1 ounce.
