Questions

A rotameter is a flow meter that measures volumetric flow of liquids and gases.

In physics, interference is a phenomenon in which two waves superpose to form a resultant wave of greater, lower, or the same amplitude. The color bands in thin films are a result of wavelength dependent interference caused by the close spacing of the surfaces of the film.

1) If they use the same cutting board/counter to cut raw chicken, and other foods with out sanitizing in between. 

2) If they have a cold, flu, or pink eye and are handling food, coughing without covering their mouth, then washing their hands.

3) If they don't properly wash their vegetables.

4) Not storing foods at proper temperatures.

And so many other reasons for Food handlers can contaminate food.