A laboratory coil-stand allows a straight copper rod of length carrying a constant…
MATHEMATICS · Multi-part · ISC · Mathematics · Physics · Magnetic Effects of Current and Magnetism
Problem
A laboratory coil-stand allows a straight copper rod of length 0.40m carrying a constant current of 8A to be rotated so that it can lie along different cardinal directions while remaining perpendicular to the local vertical line. The room has a uniform magnetic field of 0.25T directed from South to North.
(i) When the rod is oriented East–West with current flowing from East to West, calculate the magnitude of the magnetic force on it and state its direction.
(ii) The rod is now rotated to lie along the North–South line while the magnetic field remains unchanged. What will be the force on the rod in this position? Justify both mathematically and conceptually.
(iii) Keeping the rod along East–West, the current is changed to flow from West to East. Complete the following table for the two East–West positions, clearly indicating for each case the directions of (a) magnetic field, (b) current, and (c) resulting force.
(iv) From your answers above, formulate a general statement relating the simultaneous reversal of current and magnetic field to the direction of force on the conductor.