Leena had set up the experiment as shown in the figure.
She found out that the steel nail in set-up X had attracted more iron pins than the steel nail in set-up Y. What could be the reason for this?
I. The batteries used in set-up X are more expensive. There are more batteries used in set-up X. III. The number of turns of coil around the nail in set-up Y is fewer than in set-up X. IV. A longer wire was used in set-up X.
