Motional EMF Video Lessons

Concept

# Problem: A 10cm long wire is pulled along a U shaped conducting rail in a perpendicular magnetic field. The total resistance of the wire and rail is 0.20 Ω. Pulling the wire with a force of 1.0 N causes 4.0 W of power to be dissipated in the circuit. What is the speed of the wire when pulled with a force of 1.0 N? What is the strength of the magnetic field?

###### FREE Expert Solution

Induced emf:

$\overline{){\mathbf{\epsilon }}{\mathbf{=}}{\mathbf{v}}{\mathbf{B}}{\mathbf{L}}}$

Force:

$\overline{){\mathbf{F}}{\mathbf{=}}{\mathbf{i}}{\mathbf{B}}{\mathbf{L}}}$

Power:

$\overline{){\mathbf{P}}{\mathbf{=}}{\mathbf{F}}{\mathbf{·}}{\mathbf{v}}}$

Where v is the velocity, B is the magnetic field, L is the length of the conductor.

Ohm's law:

$\overline{){\mathbf{V}}{\mathbf{=}}{\mathbf{i}}{\mathbf{R}}}$

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###### Problem Details

A 10cm long wire is pulled along a U shaped conducting rail in a perpendicular magnetic field. The total resistance of the wire and rail is 0.20 Ω. Pulling the wire with a force of 1.0 N causes 4.0 W of power to be dissipated in the circuit. What is the speed of the wire when pulled with a force of 1.0 N? What is the strength of the magnetic field?