Force on a current-carrying conductor
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Under what conditions does a force act on a current-carrying conductor placed in a magnetic field?
A force acts on a current-carrying conductor in a magnetic field when the conductor is not parallel to the magnetic field lines. The force is maximized when the conductor is perpendicular to the field.
State the formula that relates the force on a current-carrying conductor to the magnetic field, current, and length.
The force F on a current-carrying conductor is given by F = BILsinθ, where B is the magnetic flux density, I is the current, L is the length of the conductor in the field, and θ is the angle between the conductor and the magnetic field.
Explain Fleming's left-hand rule and how it is used.
Fleming's left-hand rule gives the direction of the force on a current-carrying conductor in a magnetic field. With your Thumb, First finger, and Second finger at right angles, the First finger points in the direction of the Field, the Second finger points in the direction of the Current, and the Thumb points in the direction of the Force.
Define magnetic flux density (B).
Magnetic flux density (B) is defined as the force acting per unit current per unit length on a wire placed at right angles to the magnetic field. Its unit is the Tesla (T).
A 5 cm wire carrying a current of 3 A is placed perpendicular to a magnetic field of 0.6 T. Calculate the force on the wire.
Using F = BILsinθ, where θ = 90°, F = (0.6 T)(3 A)(0.05 m)(sin 90°) = 0.09 N. Therefore, the force on the wire is 0.09 N.
Describe how the magnitude of the force on a current-carrying wire changes as the angle between the wire and magnetic field varies from 0 to 90 degrees.
The force is zero when the wire is parallel (0 degrees) to the magnetic field (sin 0° = 0). The force increases as the angle increases, reaching a maximum when the wire is perpendicular (90 degrees) to the field (sin 90° = 1).
A wire of length 0.2m, carrying a current of 2A, experiences a force of 0.08N when placed in a magnetic field. If the wire is perpendicular to the field, what is the magnetic flux density?
Using F = BILsinθ, and rearranging for B: B = F / (ILsinθ). Since θ = 90°, sin θ = 1. Therefore B = 0.08N / (2A * 0.2m) = 0.2T. The magnetic flux density is 0.2 Tesla.
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