3- Photoelectric
Chapter effect
I.
The photoelectric effect certain
when
light above a
frequency is incident on a
-
released its
metal
causing electrons to be
from surface
- does not take
place if light is below thresh held
frequency (depends on metal )
- no
of electrons emitted
.
per Sec .
a
intercity y
incident light , provided light
above Thresh Freq .
.
-
emission is instantaneous
wave
theory hight cannot explain either these
things
-
g of
Phckn theory of Einstein in explain PE
light put forward by 1905 to
assumes
light is packets of Photons of hf
-
energy energy
-
,
F- =
hf and c=fX So F-
=h÷
"
Einstein said when
light iieidenh
,
each election gain energy from single
"
phaser (hf)
Electron leaves exeeds Junction
work
surface gained
-
when
energy
escape surface greeted
0 min needed election to
energy fer single
-
Max kietic
energy
-_
hf -
0 →
hf =
En to
F-minion takes
place if -
Eh 20
hf >
0
-
Jo Ctnreshhold freq ) > thresh freq grated
-
. .
Electrons be attracted back to metal
plate if so
many
can
neg .
charged electrons leave hot
plate becomes too
positive
back
and electrons are drawn .
Called
strapping potential ( Ns )
At
stopping potential ,
Ek reduced to 0 So electrons must do extra work to
overcome ,
so Ek men
= e ✗
Us
Chapter effect
I.
The photoelectric effect certain
when
light above a
frequency is incident on a
-
released its
metal
causing electrons to be
from surface
- does not take
place if light is below thresh held
frequency (depends on metal )
- no
of electrons emitted
.
per Sec .
a
intercity y
incident light , provided light
above Thresh Freq .
.
-
emission is instantaneous
wave
theory hight cannot explain either these
things
-
g of
Phckn theory of Einstein in explain PE
light put forward by 1905 to
assumes
light is packets of Photons of hf
-
energy energy
-
,
F- =
hf and c=fX So F-
=h÷
"
Einstein said when
light iieidenh
,
each election gain energy from single
"
phaser (hf)
Electron leaves exeeds Junction
work
surface gained
-
when
energy
escape surface greeted
0 min needed election to
energy fer single
-
Max kietic
energy
-_
hf -
0 →
hf =
En to
F-minion takes
place if -
Eh 20
hf >
0
-
Jo Ctnreshhold freq ) > thresh freq grated
-
. .
Electrons be attracted back to metal
plate if so
many
can
neg .
charged electrons leave hot
plate becomes too
positive
back
and electrons are drawn .
Called
strapping potential ( Ns )
At
stopping potential ,
Ek reduced to 0 So electrons must do extra work to
overcome ,
so Ek men
= e ✗
Us
