The potential difference across a metal wire is held constant. The length $l$ and the diameter $d$ of the wire are both changed. The metal used stays the same. How does the current in the wire depend on $l$ and $d$?
- AIt is directly proportional to $l$ and inversely proportional to $d$.
- BIt is directly proportional to $l$ and inversely proportional to $d^2$.
- CIt is inversely proportional to $l$ and directly proportional to $d$.
- DIt is inversely proportional to $l$ and directly proportional to $d^2$.