5.2 Electrostatics

Charge is measured in

Coulombs

Conductor	Insulator
Mat. that allows c__ to f__ thru
e.g. m__ (bc of d__ e-), g__

charge, flow, metal, delocalised, graphite

Conductor	Insulator
	Mat. that doesn’t a__ charge to f__ thru
	e.g. most n__-__ (p__, nylon etc)

allow, flow, non metals, plastic

Static Electricity
>  U__ rods on a string are always attr. to a c__ rod
>  Combing/r__ b__ on h__: e^- transferred hair → comb (friction)
>  C__ a__ rubbed w/ c__: gains _ve charge (lost e^-)
> P__ rubbed w/ cloth: gains _ve charge (gained e^-)

uncharged, charged, rubbing balloon, hair, cellulose acetate, cloth, +, polythene, -

Electrostatic Induction
Ø  Electric c__ can be induced by bringing a c__ rod near
Ø  Static charge can be detected via a g__ l__ e__

charge, charged, gold leaf electroscope

Charging by I__
Ø  __ve rod brought near m__ plate = gold leaf r__
Ø  Charged rod r__ e^- from plate down the stem
Ø  Charged rod removed = e^- r__ = orig. pos.

induction, -, metal, rises, repels, redistributes

Charging by Contact
Ø  Metal plate gets same c__ as obj.
Ø  Gold leaf rises a__ (same charge = repel)
Ø Obj. removed = charge r__ on electroscope = gold leaf remains a__ from metal plate

charge, away, remains, away

Electrostatic Attraction
Ø    Both opp. c__ & u__ objs are attr. to c__ objects e.g. paper → rod
Ø  L__ rods on buildings will:
o   Reduce c__ on the cloud = prevent l__ strikes
o     If cloud does cause lightning, thick conducting c__ carry the current → e__

charged, uncharged, charged, lightning, charge, lightning, cables, earth

Electric Field
Ø  Area where a s__ charged p__ experiences a f__
Ø  Direction of field = direction of force on _ve charge

stationary, particle, force, +