2.2.6

Electromagnets

Magnets created by the flow of electricity are called ____________?

Retentivity

The ability of a material to retain its magnetism is called __________?

Permeability

The ease with which a magnetic lines of force distribute themselves throughout a material is referred to as __________?

Armature

The moveable portion of a relay is referred to as the ________?

Clamp-on meter

11. Which device can be used to measure current in a circuit without disconnecting any wiring?

As current decreases through the loop, the weaker the magnet becomes.

12. Which of the following statements applies to an electromagnetic coil?

Mechanical shock

13. How can permanent magnets be damaged?

Ceeramic

14. Which type of magnet would be used on an escalator brake?

There is normally an air gap between the armature and iron core to ensure the relay will drop out when de-energized.

15. Which of the following statements is correct about relays?

Electrons can spin in either direction.

According to the Domain Theory of Magnetism, which of the following is correct?

From North to South

In what direction do the magnetic lines of force extend outside the magnet?

If the current through a magnetic circuit breaker is excessive, it will open the circuit.

Which of the following applications of magnetism is correct?

Magnetic lines of force form a closed loop called a magnetic circuit.

Which of the following statements is correct about lines of force extending from a magnet?

Like poles repel.

Which of the statements is correct?