 Magnetism – Gibilisco MCQs in Electronics

(Last Updated On: December 8, 2017) This is the Multiple Choice Questions (MCQs) in Chapter 8: Magnetism from the book Teach Yourself Electricity and Electronics, 5th edition by Stan Gibilisco. If you are looking for a reviewer in Electronics Engineering this will definitely help you before taking the Board Exam.

Start Practice Exam Test Questions

1. The geomagnetic field:

• A. Makes the earth like a huge horseshoe magnet.
• B. Runs exactly through the geographic poles.
• C. Is what makes a compass work.
• D. Is what makes an electromagnet work.

2. Geomagnetic lines of flux:

• A. Are horizontal at the geomagnetic equator.
• B. Are vertical at the geomagnetic equator.
• C. Are always slanted, no matter where you go.
• D. Are exactly symmetrical around the earth, even far out into space.

3. A material that can be permanently magnetized is generally said to be:

• A. Magnetic.
• B. Electromagnetic.
• C. Permanently magnetic.
• D. Ferromagnetic.

4. The force between a magnet and a piece of ferromagnetic metal that has not been magnetized:

• A. Can be either repulsive or attractive.
• B. Is never repulsive.
• C. Gets smaller as the magnet gets closer to the metal.
• D. Depends on the geomagnetic field.

5. Magnetic flux can always be attributed to:

• A. Ferromagnetic materials.
• B. Aligned atoms.
• C. Motion of charged particles.
• D. The geomagnetic field.

6. Lines of magnetic flux are said to originate:

• A. In atoms of ferromagnetic materials.
• B. At a north magnetic pole.
• C. Where the lines converge to a point.
• D. In charge carriers.

7. The magnetic flux around a straight, current-carrying wire:

• A. Gets stronger with increasing distance from the wire.
• B. Is strongest near the wire.
• C. Does not vary in strength with distance from the wire.
• D. Consists of straight lines parallel to the wire.

8. The gauss is a unit of:

• A. Overall magnetic field strength.
• B. Ampere-turns.
• C. Magnetic flux density.
• D. Magnetic power.

9. A unit of overall magnetic field quantity is the:

• A. Maxwell.
• B. Gauss.
• C. Tesla.
• D. Ampere-turn.

10. If a wire coil has 10 turns and carries 500 mA of current, what is the magnetomotive force in ampere-turns?

• A. 5000.
• B. 50.
• C. 5.0.
• D. 0.02.

11. If a wire coil has 100 turns and carries 1.30 A of current, what is the magnetomotive force in gilberts?

• A. 130.
• B. 76.9.
• C. 164.
• D. 61.0.

12. Which of the following is not generally possible in a geomagnetic storm?

• A. Charged particles streaming out from the sun.
• B. Fluctuations in the earth’s magnetic field.
• C. Disruption of electrical power transmission.
• D. Disruption of microwave radio links.

13. An ac electromagnet:

• A. Will attract only other magnetized objects.
• B. Will attract pure, unmagnetized iron.
• C. Will repel other magnetized objects.
• D. Will either attract or repel permanent magnets, depending on the polarity.

14. An advantage of an electromagnet over a permanent magnet is that:

• A. An electromagnet can be switched on and off.
• B. An electromagnet does not have specific polarity.
• C. An electromagnet requires no power source.
• D. Permanent magnets must always be cylindrical.

15. A substance with high retentivity is best suited for making:

• A. An ac electromagnet.
• B. A dc electromagnet.
• C. An electrostatic shield.
• D. A permanent magnet.

16. A relay is connected into a circuit so that a device gets a signal only when the relay coil carries current. The relay is probably:

• A. An ac relay.
• B. A dc relay.
• C. Normally closed.
• D. Normally open.

17. A device that reverses magnetic field polarity to keep a dc motor rotating is:

• A. A solenoid.
• B. An armature coil.
• C. A commutator.
• D. A field coil.

18. A high tape-recorder motor speed is generally used for:

• A. Voices.
• B. Video.
• C. Digital data.
• D. All of the above.

19. An advantage of a magnetic disk, as compared with magnetic tape, for data storage and retrieval is that:

• A. A disk lasts longer.
• B. Data can be stored and retrieved more quickly with disks than with tapes.
• C. Disks look better.
• D. Disks are less susceptible to magnetic fields.

20. A bubble memory is best suited for:

• A. A large computer.
• B. A home video entertainment system.
• C. A portable cassette player.
• D. A magnetic disk.