AQA A2 Physics Unit 4 Revision

HideShow resource information
  • Created by: S Satish
  • Created on: 18-04-13 17:07
Preview of AQA A2 Physics Unit 4 Revision

First 1647 words of the document:

Electric Fields
Char
g i
ng pl
asti
c ma t
e r
ial
s
Mo st
plast
ic materi
als
can be charged
qu i
te
easil
y by r
ubbing wi
th a
dry cl
oth.
Wh e n
an uncha r
ged
Perspex rod
is
rubbed wit
h an uncharged dr
y cl
oth,
elect
rons t
ransfer
f
rom the
rod t
o t
he cl
oth
so
the
rod become s posi
ti
vely
cha r
ged and t
he
clot
h become s
n egat
ivel
y charged.
El
ectr
ical
conductors
Me tal
s are
e l
ectr
ical
conductor
s because they
con t
ain
lot
s of
fr
ee elect
rons.
F r
ee
elect
rons are
elect
rons i
n a conduct
o r
t
ha t
move
about f
reel
y because t
he y
are
n ot
at
tached t
o a
parti
cular
a t
om.
T o
cha r
ge a me t
al,
i
t
mu st
fi
rst
be i
sol
a t
ed f
rom the Eart
h. Other
w i
se,
a ny
charge gi
ven t
o
it
i
s neut
ral
ised
by
e l
ectr
on s
tr
a nsf
erri
ng between t
h e
condu ct
or
an d
the Eart
h.
T he
isol
a t
ed conductor
can then
b e
charged by
d i
rect
contact
wit
h any
ch ar
ged
object
.
Wh en
the
isol
ated
cond uct
or
is
e ar
thed,
the el
ectrons
transf
er t
o or
fr
om t
he Earth
to
discharge/
n eut
ral
ise
the conductor
.
I
nsul
ati
n g
ma t
e r
ial
s
I nsulat
ing materi
als
are materi
al
that
cannot conduct
elect
ri
cit
y.
T hi
s i
s because they
do not
con t
ain
fr
e e
elect
rons.
A l
l
the
electr
ons i
n an i
nsulat
or ar
e att
ached
to
indi
vi
du al
at
oms .
S ome
insul
a t
ors
su ch
as Perspex or
pol
ythene are
e asy
to
cha r
ge because t
he i
r
surf
a ce
atoms easi
ly
gain
o r
l
ose
e l
ectr
on s.
Shut
tl
ing
b al
l
experimen t
T hi
s experi
me nt
sho ws
that
an elect
ri
c curr
ent
is a
fl
ow
of
ch ar
ge.
A
con duct
ing bal
l
is
suspe nded by
an i
nsu l
ati
ng t
hread between two ver
ti
cal
plat
e s.
Wh e n
a hi
g h
volt
a ge
is
app l
i
e d
across t
he t
w o
p l
ates,
t
h e
ball
bounces back
an d
fort
h bet
w een t
he t
w o
plat
es.
E ach t
ime i
t
touches the
ne gat
ive
p l
ate t
h e
ball
gai
ns some
electr
ons and become s
nega t
ivel
y charged.
I t
is
then r
epe l
l
e d
by t
h e
neg at
ive
plate
ad att
ract
ed to
the posi
ti
ve pl
a t
e.
Wh e n
it
t
ou ches
the posi
ti
ve plat
e,
the el
ectrons
on t
h e
ball
t
ransfer
to
the posi
ti
ve pl
ate so
the ball
becomes
posi
ti
vely
charged
T hi
s r
e pel
s i
t
ba c
k to
the negati
ve pl
ate.
T he
e l
ectr
on s
fr
om t
he high
volt
a ge
sup pl
y basi
call
y pass
along t
he
w i
re
to
the negati
ve pl
ate
w here t
hey ar
e
fer
ri
ed
by
the
b al
l
to
the ot
he r
pl
ate and t
hen pass al
ong t
h e
w i
re
b ack
to
the suppl
y.
A
micro amme ter
in
series
w i
th
the pl
ates shows
that
the shut
tl
ing bal
l
cau ses
a cur
rent
round t
h e ci
rcui
t.
I f
the
p l
ates
are brought
closer
toget
h er
,
the bal
l
shutt
les back
an d
fort
h more r
apidl
y and t
he
mi cr
o amme ter
r
eading i
ncreases because charge i
s f
erri
ed acr
oss at
a f
aster
rate.
I
=
Q f
= (
cha r
ge Q /
t
ime t
for
one cycl
e)
F
is
the f
requency t
h at
t
he
ball
shutt
les
back and f
ort
h
Q i
s t
he charge f
erri
ed across
the
g ap
ea ch
cycl
e wh i
ch depends on t
he
volt
age of
the
plat
e
it
l
a st
made
contact
wi
th.
Gold
leaf
el
ectr
o scope
T hi
s i
s a
d evi
ce used t
o detect
el
e ct
ri
cal
charge.
I f
a charged obj
ect
is
in cont
act wi
th t
he me t
al
cap of
the
electr
oscop e,
some
of
the char
ge
on t
h e obj
ect
tr
ansfers
t
o t
he elect
roscope so t
he gold
leaf
and t
h e
me t
al
stem att
a ched
to t
he cap gai
n t
h e
same
type of
cha r
ge
T he
leaf
ri
ses because
it
i
s r
epe l
l
e d
by t
h e
stem.
I f
another
o bj
ect
w i
th
the same
type of
charge
is
brought
n ear
the
electr
oscope, t
he l
eaf
rises
furt
h er
because t
he
obj
ect
forces
some of
the
cha r
ge on t
he
cap t
o t
ransfer
to
the l
eaf
a nd
stem.
Micr
ochips

Other pages in this set

Page 2

Preview of page 2

Here's a taster:

Ti
ny amo unt
s of
charge
on t
h e
pins
of
an
elect
roni
c chi
p can
be enough
to dest
roy
cir
cuit
s i
nsi
d e
the
chip i
f
the
pins
ar
e t
o uched
in
the pr
esence of
a charged
bod y
.…read more

Page 3

Preview of page 3

Here's a taster:

A
li
g ht
ning
conductor
is
a metal
r
od at
t
he t
op of
a t
all
bui
ldi
ng.
It
i
s c
o nnect
ed t
o t
he gr
o und
by a
thi
ck
metal
conductor
.
Wh en
a charged
cloud
is
overhead
it
cr
eates
a
very
str
ong el
ectr
ic
fi
eld
near t
he t
ip
of
the
conductor
.…read more

Page 4

Preview of page 4

Here's a taster:

Charge i
s cr
eated when t
he rubber
bel
t
rubs
against
a
pad and i
s car
ri
ed by
the
belt
up
to
the
me t
al
dome
of
the
generat
or.…read more

Page 5

Preview of page 5

Here's a taster:

For
ces
at
ri
ght
angl
es
E =
E1 +
E2
The
elect
ri
c pot
e nt
ial
V
= Q/4pi
E0r
at
a di
stance
r
fr
om Q
A
nega t
i
ve E mea ns
a f
iel
d t
hat
act
s t
owards
a negati
ve char
ge,
whereas
a
negat
ive
V me ans
a val
ue l
ess
than
0.…read more

Page 6

Preview of page 6

Here's a taster:

I
f
ther
e i
s no l
oss
of
speed
on
imp act
t
hen
v =
u and
so
the
imp act
f
orce
F = 2mu /
t
I
f
the
ini
ti
al
dir
ect
ion
o f
t
he
bal
l
is
not
perpendi
cul
ar
to
the
w al
l
2mucosx/t
i
s used
Conser
vat
ion
of
moment
um
Newton'
s t
hir
d l
aw of
mo t
ion:
when
two
object
s i
nter
act,
t…read more

Page 7

Preview of page 7

Page 8

Preview of page 8

Page 9

Preview of page 9

Here's a taster:

The var
iat
ion of
vel
o ci
ty
w i
th
ti
me
is
given
b y
the
gr
ad i
ent.
V i
s great
est when t
h e
gradient
i
s
gr
ea t
est
an d
thi
s i
s whe n
the di
splacement i
s 0.
V
i
s 0
w hen t
he gradi
en t
i
s 0
at maximum
di
splaceme nt
.…read more

Page 10

Preview of page 10

Here's a taster:

T he
tension
in
the spr
ing var
ies
from mg + kA t
o mg
­kA where
A
is
the
amp li
tude
Ma ximum tension
is
w hen x
= A
(spri
ng i
s st
retched
a s
mu ch
a s
possi
b l
e)
and
minimum tensi
on
is
w hen
x =
+A
w hen
t
he spri
ng i
s st
ret
ch ed
as l
ess as possi
ble
I
nvest
igat
ing
the osci
ll
ati…read more

Comments

Jessica

These notes were fab! Any chance you've done some for unit 5??

Luke

Great notes, are there any for unit 5?

Luke

Great notes, are there any for unit 5?

Similar Physics resources:

See all Physics resources »See all resources »