Look at the figure given below, iron filings are sprinkled on a cardboard perpendicular to which a current carrying copper wire runs. The other components of the circuit have their usual meanings. What happens to a compass at a particular point near the copper wire if the resistance of the circuit is increased?
The deflection of the compass is decreased
As the resistance of the circuit increases (with the battery being the same), the current decreases. As the current decreases, the magnetic field strength decreases and thus the deflection of the compass needle is decreased.