Rip currents can sweep away even the strongest swimmers. Rescues can quickly turn to tragedy when a rescuer gets caught in the current.

At least 100 people are killed by rip currents every year. Here's what you need to know about how to spot them and what to do if you're caught.

Alternating current (ac) or direct current (dc) circuits are capable of carrying very different currents, as illustrated by the ratings on the switch in Figure 1. This is why it’s so important ...