A thin metallic strip 40 cm long is suspended in a uniform magnetic field of so that…
MATHEMATICS · Multi-part · A Level · Mathematics · Forces and Newton's laws · Forces and Newton's laws
Problem
A thin metallic strip 40 cm long is suspended in a uniform magnetic field of 0.25T so that it makes an angle of 37∘ with the field direction. The mass per unit length of the strip is 5.0g m−1. The strip carries a current that can be varied by an adjustable power supply.
Using g=9.8m s−2, answer the questions below, showing detailed working.
(a) Calculate the current required just to balance the weight of the strip so that it is on the point of lifting.
(b) The strip is now rotated so that it is perpendicular to the magnetic field while its mass per unit length and the field remain the same. Determine the new current needed to achieve the same lifting condition.
(c) Compare the two current values obtained in parts (a) and (b) and explain the physical reason for any difference.