You said: "Bacteria (in this case, S.epidermidis) are larger than viruses (such as bacteriophage l)."

CORRECT !

	Staphylococcus epidermidis is a round bacterium (coccus) approximately 2µm (2,000nm) in diameter.
Bacteriophage l is approximately 60nm (0.06µm) in diameter and 200nm (0.2µm) long.

This is what happens during the experiment: