Electronics-Magnetism and Electrom
Electronics-Magnetism and Electrom
11. Which electromagnetic device has a flexible cone?
- A speaker
- A dc generator
- A relay
- A solenoid
12. What is the reluctance of a material that has a length of 0.045 m, a cross-sectional area of 0.015 m2, and a permeability of 2500 µWb/At·m?
- 833.33 µAt/Wb
- 0.27 At/Wb
- 1200 At/Wb
- More information is needed in order to find the reluctance.
14. What do you call the characteristic of a magnetic material whereby a change in magnetization lags the application of a magnetizing force?
- Hysteresis
- Induction
- Retentivity
- Reluctance
15. Which electromagnetic device has a movable iron core called a plunger?
- A speaker
- A dc generator
- A relay
- A solenoid
16. Which electromagnetic device contains an armature?
- A speaker
- A dc generator
- A relay
- A solenoid
17. The polarity of induced voltage while a field is collapsing is
- independent of the force creating the field
- opposite to the force creating the field
- identical to the force creating the field
- present only if the force is stationary
19. The ability of a material to maintain a magnetized state (without the presence of a magnetizing force) is called retentivity.
- TRUE
- FALSE
20. Magnetic flux flows from the north pole to the south pole within the magnet.
- TRUE
- FALSE