Section 9.7 Discharging Electrically Charged Objects

Discharging… Many everyday activities that we take for granted can generate electrical charge: –Gas pumping through a hose –An airplane flying In either example, a static charge could be very dangerous. If it was allowed to build up, it could ignite the gas or interfere with the plane’s computer system When an excess charge is removed, it is said to have been discharged or neutralized

Grounding The easiest way to discharge an object is to connect it to the Earth with a conductor When this happens, the object is said to be grounded – it shares its charge with the Earth Examples: –Gas pumps & hoses –Assembly line workers who put together computers, appliances and so on –Astronauts are ‘grounded’ to their spaceship

Discharge at a Point Grounding won’t always work – imagine trying to ground an airplane! Airplanes make use of how charges behave on the surface of conductors The shape of a conductor will affect how quickly it will discharge –Rounded objects hold charge better because they spread it out more evenly

Discharge at a Point Pointed conductors lose charges at the end of the point as the repelling force between the electrons pushes electrons off the conductor – Discharge at a Point

Static Wicks Airplanes use conductors that come to a point at one end (called Static Wicks) to discharge the plane in flight

Discharging in Other Ways 1.Humidity – water molecules in humid air (like a muggy summer day) draw the static charge out 2.Light – light particles (photons) knock electrons off of the object 3.Radioactivity – radioactive emission neutralizes electrons