ASVAB (Armed Services Vocational Aptitude Battery)General Science (GS)Medium
A technician is setting up an electromagnet. To increase the strength of the magnetic field, which of the following actions would be most effective?
- AUse a non-magnetic core material.
- BIncrease the resistance of the wire.
- CIncrease the current flowing through the coil.
- DDecrease the number of turns in the coil.
Show answer & explanationAnswer & explanation
Correct answer: C. Increase the current flowing through the coil.
The strength of an electromagnet is directly proportional to the current flowing through its coil and the number of turns in the coil. Increasing the current will therefore make the magnetic field stronger.
Why the other options are wrong
- A. Using a non-magnetic core (like air) instead of a ferromagnetic core would significantly weaken the field.
- B. Increasing resistance would decrease the current for a given voltage, thus weakening the magnetic field.
- D. Decreasing the number of turns would weaken the magnetic field.
Electromagnet Strength
The magnitude of the magnetic field produced by an electromagnet, which can be controlled by several factors.
- Directly proportional to current.
- Directly proportional to the number of turns in the coil.
- Stronger with a ferromagnetic core.
Memory trick: Current, Coils, Core make a powerful pull.