A flexible tube called an endoscope is used to view different parts of the digestive tract. When passed through the mouth (as shown on the left), an endoscope can be used to examine the esophagus, stomach, and some of the small intestine.

In an AC circuit, magnetic reversal due to phase difference between current and voltage occurs 50 or 60 times per second. A capacitor helps to improve the power factor by relieving the supply line of the reactive power.

Nitrates are reduced back into nitrogen in the soil by a process called denitrification. This process is performed by bacteria like Pseudomonas denitrificans, etc.