A conducting bar rests on two parallel horizontal rails 50 cm apart forming a square area. The resistance of the bar and the rails is assumed to be constant and equal to 0.05 Ω. A uniform magnetic field 0.5 T is perpendicular to the plane of the rails. The value of the field is uniformly reduced to zero in a time of 0.1 s. What is the maximum value of the force acting on the bar during that time?

Question

Quizplus · Accepted Answer

The induced emf (ε) is given by the rate of change of magnetic flux, ε = B * l * v, where B is the magnetic field, l is the length of the bar, and v is the velocity. The induced current (I) is ε/R, where R is the resistance. The force (F) on the bar is I * l * B. Substituting the given values, the maximum force is calculated as 6.25 N.

A Conducting Bar Rests on Two Parallel Horizontal Rails 50