A light conducting rod of length slides without friction on two parallel conducting…

PHYSICS · Single correct · A Level · Physics · Fields and their consequences · Fields and their consequences

Problem

A light conducting rod of length

0.50\,\text{m}

slides without friction on two parallel conducting rails that are

0.50\,\text{m}

apart. The rails, rod, and a

2\,\Omega

resistor at the end form a rectangular circuit lying in a uniform magnetic field of

0.40\,\text{T}

directed vertically downward. If the rod is pulled to the right with a steady speed of

3.0\,\text{m s}^{-1}

, the magnitude of the horizontal force that must be applied to keep the rod moving at this speed is closest to (a)

0.12\,\text{N}

(b)

0.06\,\text{N}

(c)

0.24\,\text{N}

(d)

0.03\,\text{N}