A compass is placed at a point 5 cm from a straight conductor carrying a current of 4 A
MATHEMATICS · Multi-part · ISC · Physics · Magnetic Effects of Current and Magnetism · Ampere's circuital law
Problem
A compass is placed at a point 5 cm from a straight conductor carrying a current of 4 A. The conductor is then adjusted so that the compass is moved to a new position 10 cm from the conductor. The experimenter wants the compass deflection (which depends on magnetic field strength) to remain unchanged.
(i) Calculate the value of the current that must now be set in the conductor so that the magnetic field strength at the new position is the same as before.
(ii) By what factor did the experimenter change the current to achieve this condition?