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12 Magnetism and the motor effect

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Question 22

An electrically operated bolt contains a permanent magnet attached to a sliding rod. A fixed straight conductor passes through the gap between the poles of the magnet, at right angles to the magnetic field.

The bolt is released only when the magnetic force on the magnet is at least 0.10 N to the left.

In a modified design, the magnet has narrower pole faces but the same magnetic flux density in the gap.

DesignCurrentCurrent directionLength of conductor inside the fieldForce on the conductor
Initial4.0 Aoriginal0.050 m0.12 N to the right
Modified6.0 Areversed0.040 mnot measured
a.

Calculate the magnetic flux density in the gap.

[2]
b.

Calculate the size of the magnetic force on the conductor in the modified design.

[2]
c.

Explain whether the bolt is released in the modified design.

[2]
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12 Magnetism and the motor effect Questions

  1. GCSE
  2. /Physics
  3. /12 Magnetism and the motor effect

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