192

THEORY OF

LIGHT

PRODUCTION

Doc. 34

ON

THE THEORY OF

LIGHT

PRODUCTION

AND

LIGHT ABSORPTION

by

A.

Einstein

[Annalen

der

Physik 20

(1906):

199-206]

In

a

study published

last

year1

I

showed

that

the

Maxwell theory

of

[2]

electricity

in

conjunction

with

the

theory of

electrons leads

to

results that

contradict the evidence

on

black-body

radiation.

By

a

route

described

in that

study,

I

was

led

to

the

view

that

light

of

frequency

v can

only be absorbed

or

emitted in

quanta of

energy (R/N)ßv,

where

R

denotes

the absolute

constant

of the

gas

equation applied

to

one

gram-molecule,

N

the

number

of

actual molecules

in

one

gram-molecule, ß

the

exponential

coefficient

of

Wien's

(and

Planck's) radiation

formula,

and

v

the

frequency

of the

light

in

question.

This

relationship

was developed

for

a

range

that

corresponds to

the

[3] range

of

validity

of Wien's

radiation formula.

At

that time it

seemed

to

me

that

in

a

certain respect Planck's

theory

of

radiation2

constituted

a

counterpart

to

my

work.

New

considerations,

which

are

being

reported in

§1

of

this

paper, showed

me,

however,

that the theore-

tical foundation

on

which

Mr.

Planck's radiation

theory

is

based

differs

from

the

one

that

would

emerge

from Maxwell's

theory

and

the

theory

of electrons,

precisely because

Planck's

theory makes

implicit

use

of the aforementioned

hypothesis

of light

quanta.

In

§2

of this

paper

I

shall

make

use

of

the

hypothesis

of

light

quanta

to

derive

a

relationship between

the Volta effect

and photoelectric

diffusion.

§1.

Planck's

theory of

radiation

and the light

quanta

In

§1

of

my

paper

cited

above

I

have

shown

that

the

molecular

theory

of

heat

combined

with the

Maxwell

theory

of electricity

and

the

theory of

1A.

Einstein,

Ann. d.

Phys.

17

(1905):

132.

2M.

Planck,

Ann. d.

Phys.

4 (1901):

561.

[1]

[4]