Switches & Circuits

(this is the switch using the mercury filament. See the pencil gripper in my left hand? Inside is the mercury filled chamber--we glued it in the gripper so it won't fall out. I'm holding it upside down, and as a result, the light is off).

(We joked that he was a Chilean miner. He actually is from Chile! And with the flashlight clipped to his hat, well, you know...)

(sometimes it was a little frustrating and the switch wouldn't work)

(an open circuit. When I close the circuit by connecting the two sides of the business card the flashlight will light up.)

(my completed switch! Eureka! It works!)

We made switches last week. In layman's terms, a switch is an electrical circuit that turns something on or off. Occupational therapists use switches to make adaptive equipment/assistive technology. As an example, we made two switches. The first switch was for a flashlight. We taped metal strips to a business card to conduct electricity and complete the circuit (for more info on circuits click here). This type of switch would be useful for someone who doesn't have the ability to push the knob on the flashlight to turn it on. With this switch, they would only have to close the business card, this requires less energy and finger movement.

The second switch we made used mercury to close the circuit. Instead of connecting two ends, with this switch you hold the tip upright or upside down. I don't know all the terminology but basically we had a glass chamber with mercury touching something that was like a metal filament. When held upright, the mercury touched the filament and closed the circuit; when held upside down the mercury did not touch the filament and opened the circuit.