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Relays, Meters, etc

Bio Med Tech course 1

What is Magnetism? A force that attracts or repels certain types of metal objects.
What are the two common permanent magnets? Horseshoe and Bar
What type of poles does a bar magnet have? North pole and South pole
All magnets have what? Lines of force called Flux Lines. Flux lines leave the north pole and enter the south pole of the magnet.
What does flux lines form? Flux lines form a magnetic field around the magnet. The more flux lines a magnet has, the stronger the magnetic field. The stronger the magnetic field, the more work or attraction the magnet can perform.
What are the two rules of magnetism? Unlike poles attract. Like poles repel
What are the two catergories that all materials fit into? Non-magnetic, Magnetic
What material is not affected by flux lines or magnetic force? Non-magnetic materials, examples are: Glass, Plastic, Wood
What material is affected by flux lines or magnetic force? Magnetic materials, examples are: Steel, Iron
What is Permeability? It is the term used to describe the willingness of a material to become magnetized. Being permeable means that the flux lines can penetrate the material.
What is Retentivity? It is the ability of a material to retain its magnetism after the magnetizing force has been removed.
What is Electromagnetism? It is a man-made form of magnetism. It's made by applying electricity to magnetic materials.
What is Magnetomotive force? It is a a small circular magnetic field that is generated when electric current passes through a conductor. It's strongest close to the conductor.
Inside a magnet, how do flux lines move? South to North
What rule is used to determine the direction of flux lines in electromagnets? Left Hand Rule. Place the left hand pointing the thumb in the direction of current flow. The curled fingers point in the direction of the flux lines.
How is the strongest magnetic field developed? Placing loops in the conductor or wrapping the conductor around a steel or magnetic core.
How is the magnetic field strength determined? The number of coil windings. The distance between windings. The amount of current. Composition of the core.
What are the three uses for electromagnets in electronics? Relays, Circuit breakers, Meters
How does the relay use an electromagnet? The electromagnet attracts the metal arm of a switch. If the switch is normally open, energizing the relay closes the switch. If the switch is normally closed, energizing the relay opens the switch.
How does a meter use electromagnetism? Electromagnetism moves the needle of the meter. When values are measure in circuits, they are indicated by the position of the needle on a meter.
What does a meter read? Voltage, Current, or Resistance.
How does meter work with a resistor? Placing the meter leads on a resistor causes the needle to point at the value of that resistor.
What happens when you place the meter leads across the voltage source? The voltage source causes the needle to point at the value of the voltage source.
What happens when you place the meter leads across an open switch? It indicates the current of the circuit
In a conductor, the direction of the flux lines is determined by the? Direction of the current flow
Increasing current flow through an electromagnet? Increases the magnetic field
What is a magnet that retains its ability to attract metal objects indefinitely called? Permanent magnet
Magnetic field strength is determined by? The number of coil windings The distance between windings The amount of current Composition of the core
Created by: 100000215936034