A constant current is sent through a helical coil. The coil:
Correct answer: A. Tends to get shorter
- A. Tends to get shorter
- B. Tends to rotate about its axis
- C. Tends to get longer
- D. Produces a zero magnetic field at its center
Explanation
A helical coil (solenoid) can be seen as a stack of parallel current loops. The currents in adjacent turns are parallel and flow in the same direction, causing them to attract each other. This cumulative attraction makes the entire coil tend to contract and get shorter.
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About Electromagnetism
Magnetic flux density and magnetic flux describe the strength of a magnetic field and the field passing through a surface. A charged particle moving through a magnetic field experiences a force perpendicular to its velocity and may follow circular or helical motion, depending on the angle between velocity and field.
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