A straight copper strip inside a prototype mini-motor has an effective length of 5.0…
MATHEMATICS · Multi-part · A Level · Mathematics · Forces and Newton's laws · Forces and Newton's laws
Problem
A straight copper strip inside a prototype mini-motor has an effective length of 5.0 cm that lies at right angles to a uniform magnetic field of 0.40 T. The designer wants the strip to experience a force of at least 0.80 N to start the rotor turning. The strip can safely carry a current of up to 30 A without overheating.
Use this information to answer the following questions.
(i) Find the minimum current that will produce the required 0.80 N force with the given 5.0 cm length.
(ii) The designer is considering increasing the strip length to 8.0 cm while keeping the current limited to 30 A. Calculate the force produced with the new length and decide whether this change meets the 0.80 N requirement.
(iii) Based on your answers, comment on which design (original or modified) is safer and more effective, giving ONE reason for your choice.